Thermoelectric semiconductor material, thermoelectric semiconductor element therefrom, thermoelectric module including thermoelectric semiconductor element and process for producing these

ABSTRACT

A metal mixture is prepared, in which an excess amount of Te is added to a (Bi—Sb) 2 Te 3  based composition. After melting the metal mixture, the molten metal is solidified on a surface of a cooling roll of which the circumferential velocity is no higher than 5 m/sec, so as to have a thickness of no less than 30 μm. Thus, a plate shaped raw thermoelectric semiconductor materials  10  are manufactured, in which Te rich phases are microscopically dispersed in complex compound semiconductor phases, and extending directions of C face of most of crystal grains are uniformly oriented. The raw thermoelectric semiconductor materials  10  are layered in the direction of the plate thickness. And the layered body is solidified and formed to form a compact  12 . After that, the compact  12  is plastically deformed in such a manner that a shear force is applied in a uniaxial direction that is approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials  10 . As a result, a thermoelectric semiconductor  17  having crystal orientation in which extending direction of C face and the don of c-axis of the hexagonal structure are approximately aligned. As a result, the crystalline orientation is improved, and the thermoelectric Figure-of-Merit is increased.

TECHNICAL FIELD

The present invention relates to a thermoelectric semiconductor materialas well as to a thermoelectric semiconductor element, a thermoelectricmodule, and manufacturing method for same that are utilized forthermoelectric cooling, thermoelectric heating, thermoelectric powergeneration or the like.

BACKGROUND ART

Devices for carrying out thermoelectric cooling, thermoelectric heatingand thermoelectric power generation using the thermoelectric propertiesof a thermoelectric semiconductor generally have a basic configurationwhere a plurality of thermoelectric modules 1 are aligned and connectedin series, as shown schematically in the example of FIG. 27. In each ofthe thermoelectric modules 1, a PN element pair is formed by joining a Ptype thermoelectric semiconductor element 2 to an N type thermoelectricsemiconductor element 3 via a metal electrode 4.

One type of thermoelectric semiconductor that forms above describedthermoelectric semiconductor elements 2 and 3 uses a complex compoundmade of one or two elements selected from bismuth (Bi) and antimony (Sb)of 5B group, and one or two elements selected from tellurium (Te) andselenium (Se) of 6B group. The thermoelectric semiconductor is made ofan alloy having a (Bi—Sb)₂(Te—Se)₃ based composition in which the ratioof a number of atoms of 5B group elements (Bi and Sb) to a number ofatoms of 6B group elements (Te and Se) is 2:3.

Above-described alloy having a (Bi—Sb)₂(Te—Se)₃ based composition forforming the thermoelectric semiconductor, has a hexagonal strut andelectrical and thermal anisotropy due to the crystal structure. It isknown that by conveying electricity or heat in the <110> direction ofthe crystal structure, that is, along C face of the hexagonal structure,excellent thermoelectric performance can be obtained, in comparison witha case where electricity or heat is conveyed in the direction of c-axis.

Conventionally, raw alloys prepared so as to have the above-describeddesired composition are heated and melted to form molten alloys.Subsequently, using a directional solidification method, such as a zonemelting method, while controlling the direction of the crystal growth sothat the crystal has an excellent thermoelectric performance along thegrowth direction, a single crystalline or a polycrystalline ingot ismanufactured as a thermoelectric semiconductor material. By a requitedworking of the ingot, such as cutting a portion having littleirregularity in the composition from the ingot and working the cutportion, an element having an excellent properties is manufactured.

However, the ingots converted to single crystal using the zone meltingmethod have significant cleavage due to their crystal structure.Therefore, when a thermoelectric semiconductor element is manufacturedby slicing or the like of the ingot as a thermoelectric semiconductormaterial, there is a problem that the insufficient mechanical strengthcause a reduction of yields by cracking or chipping. Therefore, it hasbeen desired to improve thermoelectric performance along with increasingthe strength of thermoelectric semiconductor materials forthermoelectric semiconductor elements.

In order to improve the strength and thermoelectric performance ofthermoelectric semiconductors, one technique is proposed in which aningot as a thermoelectric semiconductor material which has beenmanufactured in the same manner as described above by a directionalsolidification method, is worked by extrusion or roiling so as to applyshear force in the direction of C face of a hexagonal structure, andthereby improving the strength of the material (see, for example, PatentDocument 1).

There has been proposed several method in view of general properties ofpolycrystalline metallic material as following: Crystal grains ofpolycrystalline metallic material show dispersive distribution oforientation, the metallic material exhibits isotropy. When the crystalgrains are oriented in a specific direction as a result of a workingsuch as plastic working, crystal anisotropy of individual crystal grainsappears as macroscopic characteristics so that the metallic material asa whole exhibits anisotropy (for example, Non-Patent Document 1). Bycrushing raw alloy powder and sintering the powder, mechanical propertyof the material is improved in the sintered body. In the sintered bodycrystalline orientation is reduced, since the integration of randomlyoriented powder grains during the sintering process orientatesconstituent crystals randomly. By rolling the sintered body in adirection (see, for example, Patent Document 2), by extrusion moldingthe sintered body (see, for example, Patent Documents 3 and 4), or byplastically deforming the sintered body (see, for example PatentDocuments 5, 6, 7, 8, 9 and 10), uniformity of crystalline orientationof the sintered body is improved.

That is to say, by applying a pressing force on the above-describedsintered body, and plastically deforming the sintered body, constituentcrystals of the texture are plastically deformed and flattened in adirection perpendicular to the direction of pressing force, and thus,the crystals are oriented in such a manner that the cleavage plane areperpendicular to the direction of compression. In a rolling or a forgingby an uniaxial compression, C face of the hexagonal structure isoriented in the direction perpendicular to the direction of compressingthe sintered body (direction of pressing). In an extrusion molding, Cface of the hexagonal structure is oriented along the direction ofextrusion (direction of pressing). By this method, it is possible toprepare a thermoelectric semiconductor material in which crystals areoriented in a direction of excellent thermoelectric performance.

In general, the thermoelectric performance of the material used for themanufacture of a thermoelectric semiconductor is expressed by thefollowing equation:Z=α²·σ/κ=α²/(ρ·κ)where Z is a Figure-of-Merit, α is the Seebeck coefficient, σ iselectric conductivity, κ is thermal conductivity, and ρ is resistivity.

Accordingly, in order to increase the thermoelectric performance(Figure-of-Merit Z) of a thermoelectric semiconductor material, a rawalloy material in which the value of the Seebeck coefficient (α) or theelectric conductivity (σ) is increased or the thermal conductivity (κ)is lowered, may be utilized. Judging from this, it should be possible toincrease thermoelectric performance (Figure-of-Merit Z) by decreasingthe grain sizes of crystals and reducing the conductivity (κ). However,in the above-described techniques using a powder produced by crushing aningot of the raw alloy, the particle sizes of the powder is the grainsizes of crystals, therefore there is a limit to the miniaturiztion ofcrystal grains formed by crushing. Therefore, in order to improve thestrength and thermoelectric performance of a thermoelectricsemiconductor material, still another technique has been proposed. A rawalloy is melted into a molten alloy. A raw thermoelectric semiconductormaterial in a ribbon, foil piece or powder form is formed by a liquidquenching method such as rotational roll method in which the moltenalloy is sprayed onto the surface of a rotational roll which is beingrotated or a gas atomizing method in which the molten alloy is sprayedinto a predetermined gas flow. At that time, microscopic crystal grainsare formed within the texture of the raw thermoelectric semiconductormaterial, and high density strain and defects are introduced into thetexture. After the raw thermoelectric semiconductor material is crushedinto a powder, this raw thermoelectric semiconductor material in powderform is heat treated and solidified, and thereby a thermoelectricsemiconductor material is manufactured. By this method, during the heattreatment or the solidification process, recrystallization of crystalsoccurs ling the distortion due to the defects as a driving force, anddue to the presence of grain boundaries, the thermal conductivity (κ) islowered and thermoelectric performance (Figure-of-Merit Z) is increased(see, for example, Patent Document 11).

As the rotational velocity of a rotational roll that is used to form araw thermoelectric semiconductor material in a ribbon, foil piece orpowder form by quenching a molten alloy, it is proposed to set acircumferential velocity to be 2 to 80 m/sec, so as to effectivelygenerate microscopic crystals by quenching, and make the crystals growin the direction of heat flow (see, for example, Patent Document 12). Inthis case, a sufficient quenching speed is not achieved when thecircumferential velocity of the rotational roll is less than 2 m/sec,and a sufficient quenching speed is also not achieved when thecircumferential velocity is 80 m/sec or greater.

As the heating conditions when the raw thermoelectric semiconductormaterial in a ribbon, foil or powder form is solidified and formed, itis proposed to maintain the material at a temperature from 200 to 400°C. or at a temperature from 400 to 600° C. for 5 to 150 minutes whileapplying pressure to the material (see, for example, Patent Document13).

Another technique for increasing the thermoelectric performance of athermoelectric semiconductor material is proposed, in which Ag is addedto and mixed with a raw thermoelectric semiconductor material in aribbon, foil piece or powder form that has been formed by quenching amolten alloy of a (Bi—Sb)₂(Te—Se)₃ based raw alloy, on a rotationalroll. By subsequent sintering and solidification, Ag is distributed inthe grain boundaries, so that resistivity ρ is lowered, and thus, anincrease in the thermoelectric performance (Figure-of-Merit Z) can beachieved (see, for example, Patent Document 14).

It is known that in a rotational rolling method as the liquid quenchingmethod, a molten alloy sprayed onto the surface of a rotational roll iscooled from contact surface with the rotational roll in the directiontoward the outer periphery of the roll. Together with this quenching,the molten alloy solidifies in the direction of the film thickness. As aresult, a raw thermoelectric semiconductor material in foil form isproduced, in which C face, the base plane of the hexagonal structure ofthe crystal gains, stand in the direction of the film thickness.

Therefore, a technique for effectively using the orientation of thecrystals of a raw thermoelectric semiconductor material that has beenmanufactured by the rotational rolling method is proposed, in which theraw thermoelectric semiconductor materials are layered in the directionof the film thickness, and are sintered while pressure is applied in thedirection parallel to the direction of the film thickness, and thereby,a thermoelectric semiconductor material is manufactured (see, forexample, Patent Document 15).

Furthermore, techniques for manufacturing a thermoelectric semiconductormaterial in which crystal orientation is improved have been proposed. Ina technique, a layered body is produced by layering raw thermoelectricsemiconductor materials manufactured by a rotational rolling method, andintegrating the layered body layered in the direction of the filmthickness by applying a in the direction parallel to the layeringdirection. During the pressing for integrating the layers in thedirection parallel to the layering direction, crystal orientation ofeach layers are disordered at the interface of the layers. By applyingpressure in the direction perpendicular to the layering direction of thelayered body, such disorder of crystal orientation at the interface canbe improved (see, for example, Patent Document 16). In anothertechnique, a layered body is produced by layering raw thermoelectricsemiconductor materials in foil powder form in the direction of the filmthickness. Crystalline orientation of the layered body is improved byapplying pressure in at least three directions perpendicular to thelayering direction. Furthermore, the layered body, the crystallineorientation of which has been improved by the above-describedapplication of pressure, is formed by extrusion molding in the directionparallel to the layering direction, and thereby uniformity in theorientation of the crystals is additionally increased (see, for example,Patent Document 17).

Recently, it has been desired for a thermoelectric transducing materialto be provided with further improved performance and high reliability.Together with an increase in performance, an inclease in mechanicalstrength and excellence in workability are also desired. For example,when a thermoelectric semiconductor is used to cool a laser oscillator,N type and P type thermoelectric semiconductor elements havingdimensions of no greater than 1 mm are used as modules. Accordingly, itis required a mechanical strength sufficient to make it possible for athermoelectric semiconductor element of no greater than 1 mm indimension to be sliced from an ingot of a thermoelectric semiconductormaterial without chipping.

[List of Prior Art Documents]

(1) Patent Document 1: Japanese Unexamined Patent Application, FirstPublication No. H11-163422

(2) Pat Document 2: Japanese Unexamined Patent Application, FirstPublication No. S63-138789

(3) Patent Document 3: Japanese Unexamined Patent Application, FirstPublication No. 2000-124512

(4) Patent Document 4: Japanese Unexamined Patent Application, FirstPublication No. 2001-345487

(5) Patent Document 5: Japanese Unexamined Patent Application, FirstPublication No. 2002-118299

(6) Patent Document 6: Japanese Unexamined Patent Application, FirstPublication No. H10-178218

(7) Patent Document 7: Japanese Unexamined Patent Application, FirstPublication No. 2002-151751

(8) Patent Document 8: Japanese Unexamined Patent Application, FirstPublication No. H11-261119

(9) Patent Document 9: Japanese Unexamined Patent Application, FirstPublication No. H10-178219

(10) Patent Document 10: Japanese Unexamined Patent Application, FirstPublication No. 2002-111086

(11) Patent Document 11: Japanese Unexamined Patent Application, FirstPublication No. 2000-36627

(12) Patent Document 12: Japanese Unexamined Patent Application, FirstPublication No. 2000-286471

(13) Patent Document 13: Japanese Unexamined Patent Application, FirstPublication No. 2000-332307

(14) Patent Document 14: Japanese Unexamined Patent Application, FirstPublication No. H8-199291

(15) Patent Document 15: Japanese Patent Publication No. 2659309

(16) Patent Document 16: Japanese Unexamined Patent Application, FirstPublication No. 2001-53344

(17) Patent Document 17: Japanese Unexamined Patent Application, FirstPublication No. 2000-357821

(18) Non-Patent Document 1: “Elastic Constants of Al—Cu AlloysContaining Columnar Crystals” by Hiroshi Kato and Keiji Yoshikawa,Materials (Journal of the Society of Materials Science, Japan) Volume30, No. 331, April 1981, p. 85.

There is a problem, however, in that the mechanical strength of athermoelectric semiconductor material cannot be sufficiently enhanced,even when the thermoelectric semiconductor material is manufactured byplastically deforming an ingot of a thermoelectric semiconductor rawalloy, as shown in Patent Document 1.

At present, it is difficult to overcome the problem in which asingle-crystal or directionally solidified ingot easily cracks along thecleavage plane of the material. Even though the orientation of thecrystals is uniform, there are few methods for still increasingperformance, because the manufacturing methods are limited.

Among techniques for manufacturing a polycrystalline thermoelectricsemiconductor material, as shown in Patent Documents 2 to 10, by atechnique for plastically deforming a sintered body by rolling, by anextrusion molding, or by upsetting forging of the sintered body formedby sintering of powder produced by crushing an ingot of an alloymaterial, it should be possible to enhance the mechanical strength of athermoelectric semiconductor material. However, the size of the powderparticles determine the diameter of the crystal grains in the powder ofthe ingot, and there is a limit to the miniaturization of the crygrains. Therefore, the thermoelectric semiconductor material isdisadvantageous in reducing thermal conductivity (a) and thethermoelectric performance cannot be significantly enhanced. Inaddition, since the powder is sintered in a state in which each powderparticles are randomly oriented, by the plastic deformation of thesintered body having such disordered crystalline orientation, it isdifficult to enhance the crystalline orientation of a tenure ofthermoelectric semiconductor material.

Furthermore, in the technique disclosed in Patent Document 11, electricconductivity (σ) is increased by heat treatment or sintering in order toremove defects within the grains, and thermal conductivity (κ) isreduced due to scattering of phonons of the crystal grain boundaries.However, the grain boundaries inevitably exist in a polycrystallinebody. Therefore, at present, it is difficult to increase electricconductivity and to reduce thermal conductivity at the same time. Inaddition, there is a problem in that the electric resistance is loweredin the vicinity of grain boundaries where the impurities areconcentrated, whereas inside of the grains which mainly make up thevolume are converted to semiconductors, and thus, electric resistanceincreases.

As a rotational speed of the rotational roll for manufacturing a rawthermoelectric semiconductor material in foil or powder form, PatentDocument 12 discloses that the circumferential velocity of a rotationalroll may be set at 2 to 80 nm/sec. However, Patent Document 12 does notshow any concrete processes for manufacturing a thermoelectricsemiconductor material by solidifying and forming a raw thermoelectricsemiconductor material in foil or powder form that has been manufacturedby using a rotational roll of which the circumferential velocity hasbeen set as described above.

As a heating condition for sintering a raw thermoelectric semiconductormaterial that has been manufactured by a liquid quenching method, PatentDocument 13 discloses that the temperature may be set in a range from200 to 60° C. This is the setting of a temperature condition that allowssintering without losing uniformity in the orientation of the crystalswithin the texture of the raw thermoelectric semiconductor material, butis totally different from the temperature range for the setting of thetemperature when a raw thermoelectric semiconductor material issolidified and formed according to the present invention as describedbelow where segregation, dropping of separated phase, liquid deposition,and the like of a Te rich phase having a low melting point arecompletely prevented during solidification forming of a rawthermoelectric semiconductor material.

By a technique, as proposed in Patent Document 14, for dispersing Ag inthe crystal grain boundaries and lowering resistivity (ρ), and thereby,achieving an increase in the thermoelectric performance, Ag serves as adopant in a (Bi—Sb)₂(Te—Se)₃ based thermoelectric semiconductor.Therefore, the technique includes a problem in that the added amount ofAg must be strictly adjusted, and also includes a problem of agedeterioration.

In the technique described in Patent Document 15, raw thermoelectricsemiconductor materials in foil forms manufactured by the rotationalrolling method are layered in the direction of the film thickness andare solidified and formed. Therefore, there is a problem in which thecrystal orientation of the layered raw thermoelectric semiconductormaterial is disordered when pressure is applied in the directionparallel to the direction of the film thickness.

When raw thermoelectric semiconductor materials in foil formsmanufactured by a rotational rolling method are layered, and pressure isapplied to the layered body in the direction perpendicular to thelayering direction, and pressure is applied to layered body, asdescribed in Patent Document 16, in a direction perpendicular to thelayering direction, or as described in Patent Document 17, in at leastthree direction perpendicular to the layering direction, it should bepossible to improve crystal orientation of the texture. In these case,an improvement of crystalline orientation is achieved by making thedirection of C face of the hexagonal structure stand in the layeringdirection of the raw thermoelectric semiconductor material. However, thedirection of c-axis of the hexagonal structure in each crystal graincannot be uniformly oriented. Therefore the direction of c-axis of thehexagonal structure of the crystal grains cannot be uniformly orientedeven when an extrusion molding is additionally and sequentially carriedout by applying pressure in the layering direction, as described inPatent Document 17.

In conventional manufacturing methods for a polycrystallinethermoelectric semiconductor materials as described in Patent Documents2 to 17, powders of ingots to be solidified and formed for themanufacture of a thermoelectric semiconductor material, and rawthermoelectric semiconductor materials in ribbon, foil, and powder formproduced by a liquid quenching method have fine grain sizes. Thereforeraw thermoelectric semiconductor materials have large specific surfacearea and their surfaces are easily oxidized. In addition, even whenreduction process is carried out on each of the raw materials in orderto prevent the surface oxidation, there are many operations to be addedsuch as sealing a material in a mold without allowing contact withoxygen during sintering. Even when such additional operations arecarried out, it is difficult to reduce influence of oxidization.

In addition, since each of the above-described raw materials has finegrain size, it is difficult to increase density of the material duringsintering. For example, when a raw thermoelectric semiconductor materialin fine foil form that has been manufactured by a rotational rollingmethod and is sintered at 475° C., the increase of density is onlywithin a range of 98 to 991%. When a powder is sintered, reduction ofdensity depends on the grain size, but is limited to approximately 95%.Therefore, there is a possibility that the electric conductivity beinglowered.

Furthermore, in a general hot pressing, a fine powder is used in orderto obtain the compact texture after sintering. It is known that bulkdensity increase with decreasing particle size of powder due toincreasing amount, of air, but it is possible to gain a compactstructure by applying pressure. Therefore, in the techniques describedin Patent Documents 15 to 17, in which raw thermoelectric semiconductormaterials in foil forms manufacture by rotational rolling methods arelayered and subsequently solidified and formed, fine foils are used asthe raw thermoelectric semiconductor materials. However, since thedensification of sintered texture by hot press is a phenomena occurringas a result of powder flow and plastic deformation of powder particles,when fine foils of raw thermoelectric semiconductor materials aresolidified, as described in Patent Documents 15 to 17, a large portionof each raw thermoelectric semiconductor material is plasticallydeformed and in a great number of portions, the original crystallineorientation of the foil is disordered, and an orientation of C face iseasily disordered.

DISCLOSURE OF INVENTION

Therefore, an object of the present invention is to provide athermoelectric semiconductor material having excellent crystallineorientation in the texture, reduced oxygen concentration, and enhancedthermoelectric performance, as well as to provide a thermoelectricsemiconductor element using such a thermoelectric semiconductormaterial, a thermoelectric module using such a thermoelectric element,and manufacturing methods for same.

In order to achieve the above-described objects, the sent inventionprovides a thermoelectric semiconductor material which is produced by:layering and packing raw thermoelectric semiconductor materials made ofa raw alloy having a predetermined composition of a thermoelectricsemiconductor to form a layered body; solidifying and forming thelayered body to form a compact; applying pressure to the compact in auniaxial direction that is perpendicular or nearly perpendicular to themain layering direction of the raw thermoelectric semiconductormaterials; and thereby applying shear force in a uniaxial direction thatis approximately parallel to the main layering direction of the rawthermoelectric semiconductor materials, and plastically deforming thecompact.

When a raw alloys is contacted with the surface of a cooling member atthe time of the manufacture of the thermoelectric semiconductormaterial, a raw thermoelectric semiconductor material is achieved, inwhich C face of the hexagonal structure of the crystal grains areoriented approximately parallel to the direction of the plate thickness.When the raw thermoelectric semiconductor materials are layered in thedirection of the plate thickness to form a layered body, and thensolidified and formed, the direction of extension of C face of thecrystal grains is maintained to be oriented in the layering direction inthe compact. Furthermore, when pressure is applied to the compact insuch a manner that shear force is applied in a uniaxial directionapproximately parallel to the main layering direction of thethermoelectric semiconductor, which is approximately similar to theextending direction of C face of the crystal grains and thereby thecompact is plastically deformed, the crystal grains are flattened alongthe direction in which shear force is applied, and the extendingdirection of C face remain to be oriented in the direction of shearforce during the plastic deformation. At the same time, the directionsof c-axes of the crystal grains are oriented approximately parallel tothe direction in which pressure is applied for the plastic deformation.Accordingly, in the texture of achieved thermoelectric semiconductormaterial, both the extending direction of C face and the direction ofc-axis in the hexagonal structure of crystal grains are uniformlyoriented, and therefore high thermoelectric performance can be obtainedby setting current and heat to be conveyed in the extending direction ofC face.

Accordingly, a thermoelectric semiconductor material having an excellentthermoelectric performance can be achieved by a manufacturing method fora thermoelectric semiconductor material comprising: melting a raw alloyhaving a predetermined composition of thermoelectric semiconductor;subsequently having the molten alloy contacted with a surface of acooling member and thereby forming plate shaped raw thermoelectricsemiconductor materials; layering the plate shaped raw thermoelectricsemiconductor materials in a direction approximately parallel to adirection of the plate thickness and solidifying and forming the layeredbody into a compact; applying pressure to the compact in one of twoaxial directions which are crossing each other in a plane approximatelyperpendicular to the main layering direction of the raw thermoelectricsemiconductor materials, while preventing deformation of the compact inthe other axial direction; and thereby applying shear force in an axialdirection approximately parallel to the main layering direction of theraw thermoelectric semiconductor materials, and plastically deformingthe compact to form a thermoelectric semiconductor material.

In addition, when a thermoelectric semiconductor material has a compoundphase comprising: complex compound semiconductor phase having apredetermined stoichiometric composition of a compound thermoelectricsemiconductor, and a Te rich phase in which excess Te is added to theabove composition, crystal grain boundaries exist in the thermoelectricsemiconductor material, and crystal strain is generated due to thepresence of the compound phase of complex compound semiconductor phaseand the Te rich phase. By the introduction of crystal strain, thermalconductivity can be lowered, and therefore, the Figure-of-Merit can beincreased as a result of the lowering of thermal conductivity.

Furthermore, when a thermoelectric semiconductor material is producedby: adding excess Te to a predetermined stoichiometric composition of acompound thermoelectric semiconductor to form a raw alloy; layering andpacking plate shaped raw thermoelectric semiconductor materials made ofthe raw alloy to form a layered body; solidifying and forming thelayered body to form a compact; applying pressure to the compact in anaxial direction perpendicular or nearly perpendicular to the mainlayering direction of the raw thermoelectric semiconductor materials;and thereby applying shear force in an axial direction approximatelyparallel to the main layering direction of the raw thermoelectricsemiconductor materials, and plastically deforming the compact, thethermoelectric semiconductor material is provided with excellentcrystalline orientation in which both extending direction of C face anddirection of c-axes of the hexagonal structure of the crystal grains areapproximately uniformly oriented. In addition, due to the presence ofthe compound phase of complex compound semiconductor phase and the Terich phase, thermal conductivity can be lowered, and therefore, theFigure-of-Merit can be further increased.

Accordingly, a manufacturing method for a thermoelectric semiconductormaterial, in which a raw alloy is controlled to have a composition wherean excess Te is added to the predetermined stoichiometric composition ofa compound thermoelectric semiconductor can provide a thermoelectricsemiconductor having excellent crystalline orientation, a compound phaseof complex compound semiconductor phase and the Te rich phase, and ahigh Figure-of-Merit.

In the above described method, a P type thermoelectric semiconductormaterial having high thermoelectric performance can be produced bycontrolling the raw alloy to have a composition in which excess Te isadded to a (Bi—Sb)₂Te₃ based stoichiometric composition, concretely, bycontrolling the raw alloy to have a composition in which 0.1 to 5% ofexcess Te is added to the stoichiometric composition of a compoundthermoelectric semiconductor comprising 7 to 10 atomic % of Bi, 30 to 33atomic % of Sb, and 60 atomic % of Te.

On the other hand, a N type thermoelectric semiconductor material havinghigh thermoelectric performance as described above can be produced bycontrolling the raw alloy to have a composition in which excess Te isadded to a Bi₂(Te—Se)₃ based stoichiometric composition, concretely, bycontrolling the raw alloy to have a composition where 0.01% to 10% ofexcess Te is added to the stoichiometric composition of a compoundthermoelectric semiconductor comprising 40 atomic % of Bi, 50 to 59atomic % of Te, and 1 to 10 atomic % of Se.

Furthermore, when the solidification forming of the raw thermoelectricsemiconductor materials is carried out by applying pressure and byheating to a temperature no less than 380° C. and no higher than 500°C., the thermoelectric semiconductor material can be solidified andformed in a state in which the Te rich phase in the raw thermoelectricsemiconductor material is prevented from being converted to liquidphase, or the Te rich liquid phase is controlled to be a small amount.Therefore, a P type or N type thermoelectric semiconductor material canbe formed, having a multi phase structure of the P type or N typecomplex compound semiconductor phase dispersing microscopic Te richphases including an excess Te in the above semiconductor composition.

Moreover, in the manufacturing method, when a molten alloy of the rawalloy is contacted with the surface of a cooling member to form a plateshaped raw thermoelectric semiconductor material, the cooling rate ofthe molten alloy during solidification may be controlled to a rate bywhich 90% or more of the thickness of the plate shaped rawthermoelectric semiconductor material is not quenched. Concretely, arotational roll may be used as the cooling member, and when the plateshaped raw thermoelectric semiconductor material is formed by supplyingthe molten alloy of the raw alloy to the surface of such cooling member,the rotational roll may be rotated at a rate at which the thickness ofthe raw thermoelectric semiconductor material is controlled to be atleast no less than 30 μm. By this method, microscopic crystal nuclei areformed on the side of contact surface of the molten raw alloy and thecooling member, and the molten alloy can be slowly solidified so that,from the nuclei, large crystal grains grow in the direction of thethickness, and the raw thermoelectric semiconductor material can beformed to have a thickness of no less than 30 μm. At at time, thecrystal grains can be grown in such a manner that C face of thehexagonal structure of the crystals extend in the direction ofthickness, approximately throughout the entire thickness of the rawthermoelectric semiconductor material. When the raw alloy is made tohave a composition including excess Te, in the (Bi—Sb)₂Te₃ based P typecomplex compound semiconductor phase or in the Bi₂(Te—Se)₃ based N typecomplex compound semiconductor phase, the Te rich phases includingexcess Te in each of the above compositions can be microscopicallydispersed as separated phase without being converted to amorphous phase.Thus, the Te rich phase precipitate as hetero phase or nucreate ashetero phase nuclei within crystal grains or in grain boundaries of thecomplex compound semiconductor, and thereby a raw thermoelectricsemiconductor material having crystal strain can be achieved.

In addition, the raw thermoelectric semiconductor material has a greatthickness and a large width as a result of solidification from moltenraw alloy under slow cooling rate. Therefore, each raw thermoelectricsemiconductor material may have large volume, and therefore may have asmall specific surface area compared with a powder or the like of finesizes. Therefore, the possibility of surface oxidization is reduced, andthereby, lowering of the electric conductivity of the raw thermoelectricsemiconductor material can be prevented.

In the above described method, when heating during solidificationforming of a raw thermoelectric semiconductor material is performed bymultiple step method, the layered raw thermoelectric semiconductormaterial can be heated in such a manner that the entire body reaches adesired temperature for solidification and formation even when theheating position by the heat source is biased during heating rawthermoelectric semiconductor material for solidification and formation.Therefore, the compact formed through solidification forming of a rawthermoelectric semiconductor material can be made homogeneous throughoutthe entire body, and therefore, the thermoelectric semiconductormaterial manufactured by plastic deformation of the compact can be madehomogeneous throughout the entire body. In addition, when the raw alloyis controlled to have a composition containing excess Te, the aboveexcess component can be dissolved at the grain boundaries, and thus, thejunction at the grain boundaries can be improved.

In addition, when the plastic deformation process comprises one or moreomnidirectional hydrostatic pressure process, the occurrence of bucklingcan be prevented and an uniform deformation rate can be obtained duringthe plastic deformation of the compact. Therefore, a texture of thethermoelectric semiconductor material formed by the above describedplastic deformation can be homogenized.

A thermoelectric semiconductor element may be cut out from the abovedescribed thermoelectric semiconductor material having excellentcrystalline orientation in which both the extending direction of C faceand the direction of c-axis of the hexagonal structure of the crystalgrains are uniformly oriented. When the cut surface of thermoelectricsemiconductor element include, as a contact surface with an electrode, aplane approximately perpendicular to the uniaxial direction of shearforce application during the plastic deformation of compact to form thethermoelectric semiconductor material, it is possible to convey acurrent or heat in the direction approximately parallel to the extendingdirection of C face of the crystal grains. Therefore, the thermoelectricperformance of the thermoelectric semiconductor element can be enhanced.

Accordingly, by a manufacturing method for a thermoelectricsemiconductor element, in which a thermoelectric semiconductor materialis cut to form a thermoelectric semiconductor element so that anapproximately perpendicular plane to the uniaxial direction of shearforce application during the plastic deformation of compact may be usedas a contact sure with an electrode, the above described thermoelectricsemiconductor element having enhanced thermoelectric performance can beachieved.

A P type thermoelectric element and an N type thermoelectricsemiconductor element may be formed as above described thermoelectricsemiconductor elements having a high thermoelectric performance. A PNelement pair may be formed by joining, via a metal electrode, the P typeand N type thermoelectric semiconductor elements arranged so that theelements are align in the direction perpendicular to the axial directionof pressure application during plastic deformation of compact forforming a thermoelectric semiconductor material, and also perpendicularto the direction of shear force by the pressure application. Athermoelectric semiconductor module may be made to have theconfiguration provided by the PN element pair. In such a thermoelectricsemiconductor module, a stress caused by expansion or contraction of themetal electrode accompanied with temperature deviation during the use ofthe thermoelectric module can be applied to each of the P type and Ntype thermoelectric semiconductor elements in the direction parallel toC face of the hexagonal structure of the respective crystal grains.Therefore, even when the metal electrode expands or contracts,interlayer peeling of the crystals in the texture of the thermoelectricsemiconductor elements can be prevented, strength and durability of thethermoelectric module can be enhanced.

Accordingly, the thermoelectric module having enhanced durability andstrength can be achieved by a manufacturing method for a thermoelectricmodule comprising: preparing P type and N type thermoelectricsemiconductor elements as above described thermoelectric semiconductorelements; arranging the P type and N type thermoelectric semiconductorelements so that the elements are aligned in the direction perpendicularto the axial direction of pressure application during plasticdeformation of a compact, and also perpendicular to the direction ofshear force by the pressure application; joining the P type and N typeelements via a metal electrode to form a PN element pair.

According to the present invention as described above, excellent effectscan be obtained as following:

(1) A thermoelectric semiconductor material is produced by: layering andpacking plate shaped raw thermoelectric semiconductor materials made ofa raw alloy having a predetermined composition of a thermoelectricsemiconductor to form a layered body; solidifying and forming thelayered body to form a compact; plastically deforming the compact byapplying pressure to the compact in a uniaxial direction that isperpendicular or nearly perpendicular to the main layering direction ofthe raw thermoelectric semiconductor material, and thereby applyingshear force in a uniaxial direction that is approximately parallel tothe main layering direction of the raw thermoelectric semiconductormaterial. In such a thermoelectric semiconductor elements, it ispossible to enhance the strength by applying additional pressure toplastically deforming the compact which is formed by solidifyicationforming of plate shaped raw thermoelectric semiconductor materials. Atthe same time, not only the extending direction of C face, but also thedirection of c-axis of the hexagonal structure in the crystal gains inthe texture can be uniformly oriented, and highly excellent crystallineorientation can be achieved. Therefore, by setting the direction inwhich current and heat are conveyed in the extending direction of C faceof the crystal grains, thermoelectric performance can be enhanced.

(2) Accordingly, the above described thermoelectric semiconductormaterial may be achieved by a manufacturing method of a thermoelectricsemiconductor material comprising: melting a raw alloy having apredetermined composition of thermoelectric semiconductor; subsequentlyhaving the molten alloy contacted with the surface of a cooling memberand thereby forming plate shaped raw thermoelectric semiconductormaterials; layering the plate shaped raw thermoelectric semiconductormaterials in a direction approximately parallel to the direction of theplate thickness to form a layered body; solidifying and forming thelayered body to form a compact; applying pressure to the compact in oneof two axial directions which are crossing each other in a planeapproximately perpendicular to the main layering direction of the rawthermoelectric semiconductor materials, while preventing deformation ofthe layered by in the other axial direction; and thereby applying shearforce in an axial direction approximately parallel to the main layeringdirection of the raw thermoelectric semiconductor materials, andplastically deforming the layered body to form a thermoelectricsemiconductor material.

(3) In a thermoelectric semiconductor material having a compound phasecomprising: complex compound semiconductor phase having a predeterminedstoichiometric composition of a compound thermoelectric semiconductor,and a Te rich phase in which excess Te is added to the abovecomposition, crystal grain boundaries exist in the thermoelectricsemiconductor material, and crystal strain is generated due to thepresence of the compound phase of complex compound semiconductor phaseand the Te rich phase. By the introduction of crystal stain, thermalconductivity can be lowered, and therefore, the Figure-of-Merit can beincreased as a result of the lowering of thermal conductivity.

(4) In a thermoelectric semiconductor material produced by: addingexcess Te to the predetermined stoichiometric composition of a compoundthermoelectric semiconductor to form a raw alloy; layering and packingplate shaped raw thermoelectric semiconductor materials made of the rawalloy to form a layered body; solidifying and forming the layered bodyto form a compact; applying pressure to the compact in an axial dictionperpendicular or nearly perpendicular to the main layering direction ofthe raw thermoelectric semiconductor materials; and thereby applyingshear force in an axial direction approximately parallel to the mainlayering direction of the raw thermoelectric semiconductor materials,and plastically deforming the compact, the thermoelectric semiconductormaterial is provided with excellent crystalline orientation in whichboth extending direction of C face of the hexagonal structure of thecrystal grains and direction of c-axes of the crystal grains areapproximately uniformly oriented. In addition, due to the presence ofthe compound phase of complex compound semiconductor phase and the Terich phase, thermal conductivity can be lowered, and therefore, theFigure-of-Merit can be further increased.

(5) Accordingly, a thermoelectric semiconductor having above describedexcellent crystalline orientation, a compound phase of complex compoundsemiconductor phase and the Te rich phase, and a high Figure-of-Meritcan be achieved by a manufacturing method for a thermoelectricsemiconductor material, comprising controlling a raw alloy to have acomposition in which excess Te is added to the predeterminedstoichiometric composition of a compound thermoelectric semiconductor.

(6) In the above described method, a P type thermoelectric semiconductormaterial having high thermoelectric performance can be produced bycontrolling the raw alloy to have a composition in which excess Te isadded to a (Bi—Sb)₂Te₃ based stoichiometric composition, concretely, bycontrolling the raw alloy to nave a composition where 0.1% to 5% ofexcess Te is added to the stoichiometric composition of a compoundthermoelectric semiconductor comprising 7 to 10 atomic % of Bi, 30 to 33atomic % of Sb, and 60 atomic % of Te.

(7) On the other band, a N type thermoelectric semiconductor materialhaving above described high thermoelectric performance can be producedby controlling the raw alloy to have a composition where excess Te isadded to a Bi₂(Te—Se)₃ based stoichiometric composition, concretely, bycontrolling the raw alloy to have a composition where 0.01% to 10% ofexcess Te is added to the stoichiometric composition of a compoundthermoelectric semiconductor comprising 40 atomic % of Bi, 50 to 59atomic % of Te, and 1 to 10 atomic % of Se.

(8) Furthermore, by carrying out solidification forming of the rawthermoelectric semiconductor material by applying pressure along withheating the raw material to a temperature no less than 380° C. and nohigher than 500° C., the thermoelectric semiconductor material can besolidified and formed in a state in which the Te rich phase in the rawthermoelectric semiconductor material is prevented from being convertedto liquid phase, or the Te rich liquid phase is controlled to be a smallamount. Therefore, a P type or N type thermoelectric semiconductormaterial can be formed, having a multi phase structure of the P type orN type complex compound semiconductor phase dispersing microscopic Terich phases including an excess Te in the above semiconductorcomposition.

(9) Moreover, in the manufacturing method, when a molten alloy of theraw alloy is contacted with the surface of a cooling member to form aplate shaped raw thermoelectric semiconductor material, the cooling rateof the molten alloy during solidification may be controlled to a rate atwhich 90% or more of the thickness of the plate shaped rawthermoelectric semiconductor material is not quenched. Concretely, arotational roll may be used as the cooling member, and when the plateshaped raw thermoelectric semiconductor material is formed by supplyingthe molten alloy of the raw alloy to the surface of such cooling member,the rotational roll may be rotated at a rate at which the thickness ofthe raw thermoelectric semiconductor material is controlled to be atleast no less than 30 μm. By this method, microscopic crystal nuclei areformed on the side of contact sure of the molten raw alloy and thecooling member, and the molten alloy can be slowly solidified so that,from the nuclei, large crystal grains grow in the direction of thethickness, and the raw thermoelectric semiconductor material can beformed to have a thickness of no less than 30 μm. At that time, thecrystal grains can be grown in such a manner that C face of thehexagonal structure of the crystals extend in the direction ofthickness, approximately throughout the entire thickness of the rawthermoelectric semiconductor material. When the raw alloy is made tohave a composition including excess Te, in the (Bi—Sb)₂Te₃ based P typecomplex compound semiconductor phase or in the Bi₂(Te—Se)₃ based N typecomplex compound semiconductor phase, the Te rich phases including anexcess Te in each of the above compositions can be microscopicallydispersed as separated phase without being converted to amorphous phase.Thus, a Te rich phase precipitate as hetero phase or nucleate as heterophase nuclei within crystal grains or in grain boundaries of the complexcompound semiconductor, and thereby a raw thermoelectric semiconductormaterial having crystal strain can be achieved.

In addition, the raw thermoelectric semiconductor material has a largethickness and a large width as a result of solidification from moltenraw alloy under slow cooling rate. Therefore, each raw thermoelectricsemiconductor material may have large volume, and therefore may have asmall specific surface area compared with a powder or the like of finesizes. Therefore, the possibility of surface oxidization is reduced, andthereby, lowering of the electric conductivity of the raw thermoelectricsemiconductor material can be prevented.

(10) In the above described method, when heating during solidificationand forming process of a raw thermoelectric semiconductor material isperformed by multiple step method, the layered raw thermoelectricsemiconductor material can be heated in such a manner that the entirebody reaches a desired temperature for solidification forming even whenthe heating position by the heat source is biased during heating rawthermoelectric semiconductor material for solidification forming.Therefore, the compact formed through solidification forming of a rawthermoelectric semiconductor material can be made homogeneous throughoutthe entire body, and therefore, the thermoelectric semiconductormaterial manufactured by plastic deformation of the compact can be madehomogeneous throughout the entire body. In addition, when the raw alloyis controlled to have a composition containing excess Te, the aboveexcess component can be dissolved at the grain boundaries, and thus, thejunction at the gain boundaries can be improved

(11) In addition, when the plastic working process in the methodcomprises one or more omnidirectional hydrostatic pressure process, theoccurrence of buckling can be prevented and an uniform deformation ratecan be obtained during the plastic deformation of the compact.Therefore, a texture of the thermoelectric semiconductor material formedby the above described plastic deformation can be homogenized.

(12) A thermoelectric semiconductor element may be cut out from theabove described thermoelectric semiconductor material having excellentcrystalline orientation in which both the extending direction of C faceand the direction of c-axis of the hexagonal structure of the crystalgrains are uniformly oriented. When the cut surface of thermoelectricsemiconductor element include, as a contact surface with an electrode, aplane approximately perpendicular to the uniaxial direction of shearforce application during the plastic deformation of a compact to formthe thermoelectric semiconductor material, it is possible to convey acurrent or heat in the direction approximately parallel to the extendingdirection of C face of the crystal grains. Therefore, the thermoelectricperformance of the thermoelectric semiconductor element can be enhanced

(13) Accordingly, the above described thermoelectric semiconductorelement having enhanced thermoelectric performance can be achieved by amanufacturing method for a thermoelectric semiconductor element,comprising slicing a thermoelectric semiconductor material to form athermoelectric semiconductor element so that an approximatelyperpendicular plane to the weal direction of shear force applicationduring the plastic deformation of a compact may be used as a contactsurface with an electrode.

(14) A P type thermoelectric element and an N type thermoelectricsemiconductor element may be formed as above described thermoelectricsemiconductor elements having a high the thermoelectric performance. APN element pair may be formed by joining, via a metal electrode, the Ptype and N type thermoelectric semiconductor elements arranged so thatthe elements are aligned in the direction perpendicular to the axialdirection of pressure application during plastic deformation of acompact for forming a thermoelectric semiconductor material, and alsoperpendicular to the direction of shear force by the pressureapplication. A thermoelectric semiconductor module may be made to havethe configuration provided by the above described PN element pair. Insuch a thermoelectric semiconductor module, a stress caused by expansionor contraction of the metal electrode accompanied with temperaturedeviation during the use of the thermoelectric module can be applied toeach of the P type and N type thermoelectric semiconductor elements inthe direction parallel to C face of the hexagonal structure of therespective crystal grains. Therefore, even when the metal electrodeexpands or contracts, interlayer peeling of the crystals in the textureof the thermoelectric semiconductor elements can be prevented, strengthand durability of the thermoelectric module can be

(15) Accordingly, the thermoelectric module having enhanced durabilityand strength can be achieved by a manufacturing method for athermoelectric module comprising: preparing P type and N typethermoelectric semiconductor elements as above described thermoelectricsemiconductor elements; arranging the P type and N type thermoelectricsemiconductor elements so that the elements are aligned in the directionperpendicular to the axial direction of pressure application duringplastic deformation of a compact, and also perpendicular to thedirection of shear force by the pressure application; joining the P typeand N type elements via a metal electrode to form a PN element pair.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart showing an embodiment of manufacturing method fora thermoelectric semiconductor material according to the presentinvention.

FIG. 2 is a diagram schematically showing a device used in the slowcooling foil manufacturing process of FIG. 1.

FIG. 3 is a schematic perspective diagram showing a raw thermoelectricsemiconductor material formed in the slow cooling foil manufacturingprocess of FIG. 1.

FIG. 4 is a graph showing the correlation between the thickness of a rawthermoelectric semiconductor material formed in the slow cooling foilmanufacturing process of FIG. 1 and the circumferential velocity of thecooling roll.

FIG. 5 is a graph showing the correlation between the width of the rawthermoelectric semiconductor material formed in the slow cooling foilmanufacturing process of FIG. 1 and the circumferential velocity of thecooling roll.

FIG. 6A is a photograph showing the cross section of the structure of araw thermoelectric semiconductor material formed in the slow coolingfoil manufacturing process of FIG. 1;

FIG. 6B is a photograph of the structure of a raw thermoelectricsemiconductor material formed in the slow cooling foil manufacturingprocess of FIG. 1 showing a surface of the raw thermoelectricsemiconductor material opposite to the contact surface with a rotationalroll.

FIG. 7A is a schematic perspective diagram showing a compact formed inthe solidification forming process of FIG. 1.

FIG. 7B is a perspective diagram of a compact formed in a solidificationforming process of FIG. 1 schematically showing the layered structure ofa raw thermoelectric semiconductor material.

FIG. 7C is an enlarged perspective diagram showing a partial crosssection of a compact shown in FIG. 7B.

FIG. 8A is a diagram showing a plastic working device used in theplastically deforming process of FIG. 1 and is a schematic crosssectional side view of the device in the initial state beforeplastically deforming the compact.

FIG. 8B is a diagram showing the device of FIG. 8A as viewed along theline A-A in the direction of the arrows;

FIG. 8C is a diagram showing a plastic working device used in theplastically deforming process of FIG. 1 and is a schematic crosssectional side view of the device in a state in which a thermoelectricsemiconductor material is formed by plastic deformation of a compact.

FIG. 8D is a diagram corresponding to FIG. 8B showing another type ofthe plastic working device used in the plastically deforming process ofFIG. 1 and is provided with a ring for fixing the position.

FIG. 9A is a schematic perspective diagram showing a thermoelectricsemiconductor material formed in the plastically deforming process ofFIG. 1.

FIG. 9B is a perspective diagram schematically showing the crystallineorientation of a thermoelectric semiconductor material formed in theplastically deforming process of FIG. 1;

FIG. 10 is a graph showing the correlation between the circumferentialvelocity of the cooling roll in the slow cooling foil manufacturingprocess of FIG. 1 and the thermal conductivity of the thermoelectricsemiconductor material formed in the plastically deforming process ofFIG. 1 using a raw thermoelectric semiconductor material formed in theslow cooling foil manufacturing process.

FIG. 11 is a graph showing the correlation between the circumferentialvelocity of the cooling roll in a slow cooling foil manufacturingprocess of FIG. 1 and the electric conductivity of a thermoelectricsemiconductor material that is formed in the plastically deformingprocess of FIG. 1 using a raw thermoelectric semiconductor materialformed in this slow cooling foil manufacturing process.

FIG. 12 is a graph showing the correlation between the circumferentialvelocity of the cooling roll in a slow cooling foil manufacturingprocess of FIG. 1 and the Seebeck coefficient of a thermoelectricsemiconductor material formed in a plastically deforming process of FIG.1 using the raw thermoelectric semiconductor material formed in the slowcooling foil manufacturing process.

FIG. 13 is a graph showing the correlation between the circumferentialvelocity of a cooling roll in a slow cooling foil manufacturing processof FIG. 1 and the carrier concentration of the thermoelectricsemiconductor material formed in the plastically deforming process ofFIG. 1 using a raw thermoelectric semiconductor material formed in theslow cooling foil manufacturing process.

FIG. 14 is a graph showing the correlation between the circumferentialvelocity of the cooling roll in the slow cooling foil manufacturingprocess of FIG. 1 and the Figure-of-Merit of the thermoelectricsemiconductor material formed in the plastically deforming process ofFIG. 1 using the raw thermoelectric semiconductor material formed inthis slow cooling foil manufacturing process;

FIG. 15 is a graph showing the correlation between the thickness and theoxygen concentration of the raw thermoelectric semiconductor materialformed in a slow cooling foil manufacturing process of FIG. 1.

FIG. 16 is a graph showing the correlation between the width and oxygenconcentration of the raw thermoelectric semiconductor material that isformed in a slow cooling foil manufacturing process of FIG. 1.

FIG. 17 is a graph showing the correlation between the circumferentialvelocity of the cooling roll in a slow cooling foil manufacturingprocess of FIG. 1 and the oxygen concentration of the raw thermoelectricsemiconductor material formed in the slow cooling foil manufacturingprocess.

FIG. 18 is a graph showing the correlation between the oxygenconcentration in the raw thermoelectric semiconductor material that ismanufactured in the slow cooling foil manufacturing process of FIG. 1and the Figure-of-Merit of the thermoelectric semiconductor materialformed using the raw thermoelectric semiconductor material.

FIG. 19 is a flow chart showing another embodiment of a manufacturingmethod for the thermoelectric semiconductor material according to thepresent invention;

FIG. 20A is a diagram showing a plastic working device used for anomnidirectional hydrostatic pressure process of FIG. 19 and is aschematic cross sectional side view of the device in the initial statebefore the plastic deformation of a compact.

FIG. 20B is a diagram showing the device of FIG. 20A as viewed alongline B-B in the direction of the arrows.

FIG. 20C is a diagram showing the plastic working device used for anomnidirectional hydrostatic pressure process of FIG. 19 and is aschematic cross sectional side view of the device in a state in whichomnidirectional hydrostatic pressure is applied to a compact that hasbeen plastically deformed by a predetermined amount.

FIG. 21 is a schematic perspective diagram showing steps of themanufacturing method for a thermoelectric semiconductor element of thepresent invention, and showing a state for slicing a thermoelectricsemiconductor material, a sliced wafer, and a thermoelectricsemiconductor element cut out from a wafer.

FIG. 22 is a schematic perspective diagram showing an embodiment of athermoelectric module according to the present invention.

FIG. 23 is a schematic perspective diagram showing a comparative examplefor a thermoelectric module of FIG. 22.

FIG. 24A is a schematic cross sectional side view showing anotherexample of a plastic working device used in a plastically deformingprocess of FIG. 1.

FIG. 24B is a diagram showing the device of FIG. 24A along line C-C inthe direction of the arrows.

FIG. 25A is a schematic diagram showing an example of the plasticallydeforming process of FIG. 1 by another device, and showing a state inwhich a compact is plastically deformed by a high pressure press.

FIG. 25B is a schematic diagram showing an example of the plasticallydeforming process of FIG. 1 by another device, and showing a state inwhich a compact is plastically deformed by a rolling device.

FIG. 26 is a graph showing the results of the comparison of thethermoelectric performance of a thermoelectric module manufactured bythe manufacturing method of the present invention with that of athermoelectric module manufactured by another manufacturing method.

FIG. 27 is a perspective diagram schematically showing an example of aconventional thermoelectric module.

BEST MODE FOR CARRYING OUT THE INVENTION

In the following embodiments of the present invention are explained withreference to the drawings.

FIGS. 1 to 18 show an embodiment of manufacturing method for athermoelectric semiconductor material according to the presentinvention. As shown in the flow chart of FIG. 1, basically thethermoelectric semiconductor material is manufactured by: preparing analloy by mixing, in a predetermined ratio, respective metals composing araw alloy of a thermoelectric semiconductor; melting the metals to forma molten alloy; slowly cooling the molten alloy by an undermentionedcooling method at a rate at which 90% or more of the thickness of theraw thermoelectric semiconductor material is not quenched; solidifyingthe molten alloy to form a thin plate shaped foils (slow cooling foils)as raw thermoelectric semiconductor materials; after layering andpacking the slow cooling foils produced as raw thermoelectricsemiconductor materials so that the foils are layered in a mold, in thedirection of plate thickness, solidification forming the layered foilsunder an undermentioned predetermined heating condition to form acompact; next, plastically deforming the compact by applying a load insuch a manner that a shear stress is applied in an uniaxial directionapproximately parallel to the main layering direction of the rawthermoelectric semiconductor material, and thereby manufacturing athermoelectric semiconductor material.

Concrete manufacturing methods for an N type thermoelectricsemiconductor material and an N type semiconductor element are describedas follows.

Firstly, to prepare a stoichiometric composition of a raw alloy of an Ntype thermoelectric semiconductor in a component mixing process I, Bi,Se and Te are weighed so that the raw alloy contains 40 atomic % of Bi,1 to 10 atomic % of Se, and 50 to 59 atomic % of Te. The weighed metalsare mixed to obtain a Bi₂(Te—Se)₃ based composition. Furthermore excessTe is aided so that 0.01 to 10% by weight of Te is contained in theentire Bi₂(Te—Se)₃ based component, and thus an alloy having anonstoichiometric composition with excess Te is prepared. At that time,a predetermined amount of dopant for forming an N type thermoelectricsemiconductor, such as Hg, Ag, Cu or a halogen dopant, may be added.

Next, in a slow cooling foil manufacturing process II, as shown in FIG.2, a metal mixture that has been mixed and prepared in theabove-described component mixing process I is put into a meltingcrucible 6 made of quartz. The crucible is introduced into a container 5which can hold a low oxygen concentration atmosphere such as a reductiongas atmosphere, an inert gas atmosphere or a vacuum. The crucible isheated by a heating coil 7 so as to melt the metal to form a moltenalloy 8. After that, the molten alloy 8 is supplied to the surface of arotational roll 9 such as a water cooled roll. The rotational roll actas cooling member and the molten alloy is solidified. So as to form slowcooling foils as raw thermoelectric semiconductor materials 10 of atleast 30 μm or more in thickness, the molten alloy is supplied from anozzle which has a predetermined diameter, for example 0.5 mm, and isprovided at the bottom of the melting crucible 6, to the surface of therotational roll 9 rotating at a slow rate at which the circumferencevelocity is no higher than 5 m/sec, and thereby the molten alloy issolidified. By this process, slow cooling foils as raw thermoelectricsemiconductor materials 10 in thin plate shaped forms arm manufacturedas shown in FIG. 3.

It is preferable to set the rotational velocity of the rotational roll 9so that the circumferential velocity is no higher than 2 m/sec. When thecircumference velocity of the rotational roll 9 is set to be no higherthan 5 m/sec, as it is obviously shown in the graph of FIG. 4, thethickness of the slow cooling foil manufactured as a raw thermoelectricsemiconductor material 10 can be made as thick as 30 μm or more. Inaddition, when molten alloy 8 is solidified on the surface of therotational roll 9 to form the raw thermoelectric semiconductor material10, the molten alloy can be solidified at a rate by which 90% or more ofthe thickness of the raw thermoelectric semiconductor material is notquenched. Therefore, as shown in FIG. 3, crystal grains 11 formed in thetexture of the raw thermoelectric semiconductor material 10 may have alength extending throughout entire thickness of the slow cooling foil asthe raw thermoelectric semiconductor material 10, and thus, rawthermoelectric semiconductor material 10 having an excellent crystallineorientation can be formed. Furthermore, when the circumferentialvelocity of rotational roll 9 is set to be no greater than 2 m/sec, thethickness of raw thermoelectric semiconductor material 10 can beeffectively increased to a value of no less than approximately 70 μm.Thus lengths of crystal grains 11 can be additionally increased, and thecrystalline orientation can be further improved. In addition, asdescribed above, when the rotational speed of rotational roll 9 is setso that the circumferential velocity becomes no greater than 5 m/sec, asit is obvious from the graph shown in FIG. 5, the width of the slowcooling foils manufactured as the raw thermoelectric semiconductormaterials 10 can be increased, and the volumes of each rawthermoelectric semiconductor material 10 can be increased.

Crystal grains 11 in the texture of raw thermoelectric semiconductormaterial 10 are schematically illustrated as hexagons in FIG. 3. Thesehexagons do not show the actual crystal lattice in the hexagonalstructure of the above-described crystal grains 11, but for conveniencein explanation, schematically show the direction of C face of thehexagonal structure of the crystal grains 11 by the hexagons, and inaddition, by the flattened direction of the hexagons, schematicallyindicate the direction in which crystal grains 11 are flattened, thatis, the direction in which the crystal grains are oriented. This can beapplied to the following figures.

As a result of this, molten alloy 8 of the raw alloy is supplied to therotational roll 9 and is slowly cooled, and thereby is slowly andsequentially cooled from the contact surface with the rotational rolltoward the outer periphery of the roll, that is in the direction of thethickness of molten alloy 8. As a result, as shown in FIG. 3, thecrystal structures of the complex compound semiconductor phases ofBi₂Te₃ and Bi₂Se₃ are respectively solidified and crystallized, in whichextending direction of C face of the hexagonal structure of crystalgrains 11 are mainly oriented in the direction of the plate thickness(the direction shown by arrow t in the figure). At the same time, sinceTe is added to the above molten alloy 8 so that excess Te is added tothe Bi₂(Te—Se)₃ based stoichiometric composition, Te rich phasesincluding excess Te in the composition of Bi₂Te₃ or Bi₂Se₃ aremicroscopically dispersed as a non-amorphous separated phase in thecrystal grains and grain boundaries of the respective complex compoundsemiconductor phases of Bi₂Te₃ and Bi₂Se₃. Thus a raw thermoelectricsemiconductor material 10 that is thought to have a structure dispersingmicroscopic Te-rich phase, that is, a structure having crystal strain byprecipitation of hetero phase (Te-rich pahse) or by nucleation of heteropahse nuclei within crystal grains and grain boundaries of theBi₂(Te—Se)₃ based complex compound semiconductor, can be achieved.

FIGS. 6A and 6B show scanning electron microscope (SEM) images of atexture of raw thermoelectric semiconductor material 10 manufactured bythe above-described slow cooling foil mating process II. FIG. 6A shows across section of the raw thermoelectric semiconductor material 10. Inthis figure, contact surface with the rotational roll 9 is placed on theupper side. FIG. 6B shows the surface structure of the rawthermoelectric semiconductor material 10 opposite to the contact surfacewith the rotational roll.

As is clear from the FIG. 6A, raw thermoelectric semiconductor materials10 having a thickness of no less than 30 μm can be formed in the slowcooling foil manufacturing process II. The contact surface with therotational roll 9 shows fine crystal gains formed by quenching of moltenalloy 8 by the contact with the rotational roll 9. These fine crystalgrains are formed only in the surface region on the side of the contactsurface with the rotational roll 9, whereas other than the surfaceregion having the fine crystal grains, in the region of 90% or more ofthe thickness, large crystal grams 11 oriented in the direction of theplate thickness throughout the entire thickness of the plate can beformed.

In addition, as is clear from FIG. 6B, the raw thermoelectricsemiconductor material 10 have a textual structure in which crystalgrains 11 a of hetero phases (Te rich phases) are generated within thegrains and grain boundaries of crystal grains 11 of the Bi₂(Te—Se)₃based complex compound semiconductor or the like, which are flattenedand oriented so as to extend in direction of the plate thickness. Powderparticles of small grain sizes mixed in the raw thermoelectricsemiconductor materials 10 manufactured by the slow cooling foilmanufacturing process II may be removed in advance by sieving, beforethe raw thermoelectric semiconductor materials being sent to thefollowing solidification forming process III.

Next, in the solidification forming process III, the slow cooling foilsof raw thermoelectric semiconductor materials 10 manufactured by theslow cooling foil manufacturing process II are layered in the directionapproximately parallel to the direction of the plate thickness (thedirection of arrow t) and are packed in a mold, not shown, within acontainer (not shown) that can hold a low oxygen concentrationatmosphere such as a reduction gas atmosphere, an inert gas atmosphereor a vacuum of 10 Pa or less. After that, the foils are sintered andpressurized and are solidified and formed to have a predetermined form.For example, a rectangular solid shaped compact 12 having apredetermined width corresponding to a spacing between restrictingmembers 15 in a plastic working device 13 used in the after-mentionedplastically deforming process IV is manufacturing as shown in FIGS. 7A,7B, and 7C.

FIG. 7B schematically shows a layered structure of the slow coolingfoils of a raw thermoelectric semiconductor material 10 as a basicconfiguration of the structure of the compact 12. FIG. 7C shows anenlarged view of the layered structure of raw thermoelectricsemiconductor materials 10 of the FIG. 7B.

As conditions for the above-described sintering process along withapplying predetermined pressure, for example, pressure of no less than14.7 MPa, and heat is applied in a manner such that the Te rich phaseexisting in the thermoelectric semiconductor material manufactured inthe above-described slow cooling foil manufacturing process II isprevented from complete segregation, formation of deferent phase, orliquid phase precipitation. Since the Te-rich phase have a possibilityto form a liquid phase at a temperature of approximately 420° C.,sintering is carried out by heating to a temperature condition of nohigher than 500° C., preferably no lower than 420° C. and no higher than450° C., and keeping at the temperature for about 5 seconds to 5minutes.

The lower limit of the temperature condition in the sintering is nolower than 380° C. This is because the density of compact 12 does notincrease when the sintering temperature is lower than 380° C.

At the time of the above-described sintering, multi step heating iscarried out so that the entirety of the object for sintering can beapproximately uniformly heated to the predetermined sinteringtemperature without causing heterogeneous temperature distribution inthe object.

In the multi step heating, when an object for sintering is heated to thepredetermined sintering temperature using a predetermined heatingsource, not shown, heating step is controlled to comprise one orperiods, for example, for no less than 10 seconds, of stopping heatingby the heat source for a predetermined period of time, or of temporallychanging the heating by the heat source so that the heating rate of theobject of sintering is slowed down, and thereby homogenizing thetemperature of the whole object for sintering by heat conduction duringthe above-described stopping heating or slowing heating rate periods.After homogenizing the temperature of the whole body in the process ofheating, by further heating the object for sintering, the object isheated almost homogeneously to the final temperature, as the sinteringtemperature.

Accordingly, by homogenizing the temperature of the entire object forsintering in the process of heating, even though the heating position bythe heat source is biased, uneven temperature distribution can berestrained when the temperature reaches the sintering temperature. Inthis case, as a heating device (heating furnace) for the sintering,conventional hot pressing, energized hot pressing or pulse energized hotpressing may be used. In addition, the above-described periods forstopping heating, or slowing the heating rate are not limited to 10seconds or higher, but may be arbitrarily set depending on the heatingability of the heat source, the size of the object for sintering, or thelike.

The slow cooling foils as raw thermoelectric semiconductor materials 10formed in the above-described slow cooling foil manufacturing process IIhave large widths and thicknesses, and therefore, their layered bodyhave a large volume and many interstices. By layering and subsequentlysintering along with pressing the raw thermoelectric semiconductormaterials 10 in the solidification forming process III, atoms of therespective raw thermoelectric semiconductor materials 10 migrate so asto fill in the interstices between the raw thermoelectric semiconductormaterials 10. Together with the migration of atoms, the respective rawthermoelectric semiconductor materials 10 are plastically deformed so asto make contact with each other and fill in the interstices between theraw thermoelectric semiconductor materials 10. Therefore, rawthermoelectric semiconductor materials 10 which are made to make contactwith each other through the plastic deformation are joined to each othervia the interfaces.

At that time, although the deformation of raw thermoelectricsemiconductor menials 10 slightly disarrange the orientation of C faceof crystal grains 11 that have been oriented approximately in thedirection of plate thickness of the raw thermoelectric semiconductormaterial 10, that disordering does not cause a volumetric breakdown ofthe whole body. Accordingly, as shown in FIG. 7B, in the slow coolingfoils of raw thermoelectric semiconductor material 10 constructing thecompact 12, the orientation of crystal grains 11 is maintained as sameas the crystalline orientation (in the direction of arrow t) of a singlepiece of raw thermoelectric semiconductor material 10 shown in FIG. 3.Therefore, it is possible to prevent the possibility of mass breakdownof the orientation of C face of the crystal grains, which could not beavoided in prior art, in which very fine raw thermoelectricsemiconductor materials were sintered.

In addition, in the formation of the compact 12, slow cooling foils ofraw thermoelectric semiconductor material 10 having a large thicknessand large width are layered in the direction approximately parallel tothe direction of the plate thickness, and subsequently solidified andformed. Therefore, the interstices between the raw thermoelectricsemiconductor materials 10 can be easily reduced, and it becomespossible to increase density of the compact 12 to approximately 99.8% orhigher of the density of an ideal crystal structure of the complexcompound semiconductor of the same composition.

Furthermore, no or only little amount of Te rich phase in the rawthermoelectric semiconductor material 10 is converted to a liquid phaseduring sintering. Therefore, the compact 12 is formed so as to maintainthe teal structure of a complex compound semiconductor phase having thecomposition of Bi₂Te₃ and Bi₂Se₃ dispersing microscopic Te rich phasesincluding excess Te in the above-described compositions. In addition,together with heating during the sintering process, the Te rich phasespartially occur in the interfaces between the slow cooling foils as rawthermoelectric semiconductor materials 10.

After that, in the plastically deforming process IV, a plastic workingdevice 13 is prepared to comprise an air-tight container, not shown,that can hold a low oxygen concentration atmosphere, for example, havingpartial pressure of oxygen no higher than 0.2 Pa by a reduction gasatmosphere, an inert gas atmosphere or a vacuum. In such a container, asshown in FIGS. 8A, 8B, and 8C, a pair of restricting members 15 in plateform having approximately parallel surfaces opposed to each other areplaced intervening a predetermined spacing at either side of a base 14.The spacing corresponds to the width of the above-described compact 12(dimension of the compact 12 in one axial direction of the two axialdirections crossing in a plane perpendicular to the main layeringdirection of raw thermoelectric semiconductor material 10 forming thecompact 12). Inner side of the restricting members 15 placed in thelateral direction, a punch 16 is placed so that it can slide in theupward and downward directions. In addition, by a vertical driving unit,not shown, along with being added with a load, the punch 16 can belowered from the upper position above the restricting members 15 placedin the lateral direction to the lower position inside between therestricting members 15. Heating units are provided to predeterminedpositions of the base 14, restricting members 15, and punch 16. As shownin FIG. 8A, in a state where the punch 16 is pulled up to the upperposition above the restricting members 15, the compact 12 formed in thesolidification forming process III is placed in the center portionbetween the restricting members 15 so that the longitudinal direction ofthis compact 12 is vertically directed. At the same time, the compact 12is arranged so that the layering direction of the raw thermoelectricsemiconductor materials 10 forming the compact 12 (direction of arrow t,same as the direction of the plate thickness of the raw thermoelectricsemiconductor material 10) is set to be parallel to the restrictingmembers 15 placed in the lateral direction, and both sides of thecompact in the direction of the width are placed so as to make contactwith the inner surfaces of the restricting members 15 placed in thelateral direction. Next, along with heating the compact 12 at atemperature that is no higher than 470° C., preferably no higher than450° C. by the heating units, pressure of a predetermined load isapplied to the compact 12 by lowering the punch 16 by the verticaldriving unit as shown in two-dot chain lines of FIG. 8A. As a result, asshown in FIG. 8C, the compact 12 is plastically deformed so as to beexpanded in a uniaxial direction parallel to the layering direction ofraw thermoelectric semiconductor materials 10, and a thermoelectricsemiconductor material 17 of rectangular solid is manufactured.

In the above-described plastic working device 13, when a pressing forceis applied from above to compact 12 by punch 16, since deformation ofthe compact 12 in the direction of its width is restricted by therestricting members 15 placed in the lateral direction, deformation ofthe compact 12 is allowed only in the direction parallel to therestricting members 15, that is to say, in the layering direction of rawthermoelectric semiconductor materials 10 (in the direction of arrowst), and therefore a shear force is applied in a uniaxial directionparallel to the layering direction. As a result, in the slow coolingfoils of raw thermoelectric semiconductor material 10 constructing thecompact 12 before the above-described plastic deformation, interfaces oflayers are deformed and adjacent layers are integrated to each other.Crystal grains being oriented so that C face of the hexagonal structureextend in the direction parallel to the direction of the plate thicknessof raw thermoelectric semiconductor materials 10 in the compact 12, areplastically deformed to be flattened in the direction in which the shearforce is applied, and are oriented so that the cleavage planes areperpendicular to the direction of the pressure.

Accordingly, as shown in FIG. 9A, in the texture of thermoelectricsemiconductor materiel 17 formed after the plastically deforming of thecompact 12, crystal grains are oriented as schematically shown in FIG.9B. The crystal grains 11 are respectively deformed so that C face ofthe hexagonal structure extends in the expanding direction of thecompact 12, that is to say, in the direction parallel to the layeringdirection of raw thermoelectric semiconductor materials 10 in thecompact 12 before the deformation (in the direction of arrows t). At thesame time, most of the crystal grains 11 are oriented so that thedirection of c-axes are aligned in the direction of compression (in thedirection of arrows p) in the plastically forming process. The hexagonsin FIG. 9B only indicate the orientation of the crystal grains 11, butdo not reflect the actual sizes of the crystal grains 11.

During the plastically deformation of the compact 12 in the plasticwowing device 13, strong outward sums is applied to the restrictingmembers 15 placed in the lateral direction. Therefore, as show in FIG.8D, a fixing position ring 15 a may be provided so as to surround theouter periphery of the restricting members 15 placed in the lateraldirection. By this configuration, the stress that is applied to therestricting members 15 placed in the lateral direction may be endured bythe fixing position ring 15 a.

As described above, in the N type thermoelectric semiconductor material17 of the present invention, by slowly cooling and solidifying moltenraw alloy 8 using rotational roll 9, crystal grins 11 are oriented inthe direction of the plate thickness, and made long to extendingthroughout entire plate thickness, and thereby have an improvedcrystalline orientation. In addition raw thermoelectric semiconductormaterials 10 have a structure in which Te rich phases are precipitated,as hetero phase low melting point, in the crystal grains or grainboundaries. Along with maintaining the crystalline orientation and thetextual structure comprising Bi₂(Te—Se)₃ based complex compoundsemiconductor phases dispersing the above-described Te-rich phase, theraw thermoelectric semiconductor materials 10 are solidified and formedto form the compact. The compact is expanded only in a uniaxialdirection approximately parallel to the direction of the plate thicknessof the raw thermoelectric semiconductor material 10, that is, thelayering direction of the raw thermoelectric semiconductor material 10.Because of the above-described configuration, in the N typethermoelectric semiconductor material, crystal strain is generated bythe presence of the hetero phase within crystal grains and grainboundaries, as well as by the presence of grin boundaries. By thegeneration of the crystal strain, thermal conductivity can be reduced.In addition, since the directions of c-axes and extending directions ofC face of the hexagonal structure of the crystal grains 11 areapproximately uniformly oriented throughout the entire body of thethermoelectric semiconductor material 17, thermoelectric performance (ofwhich the Figure-of-Merit is Z) can be enhanced by setting the directionfor conveying a current and heat to the extending direction of C face ofthe crystal grains 11.

As shown in FIG. 4, the circumferential velocity of rotational roll 9 isset at a rate as low as 5 m/sec, so that raw thermoelectricsemiconductor materials 10 having thickness of no less than 30 μm can beachieved. By using a rotational roll of the above-described low speedrotation, the thermal conductivity (κ) of manufactured thermoelectricsemiconductor material 17 can be increased compared to the case usingraw thermoelectric semiconductor material 10 made by the rotational roll9 of high rotational speed. As shown in FIG. 10, the above descriptionis clearly shown in the relationship, between the rotational speed ofrotational roll 9 during the manufacture of slow cooling foils as rawthermoelectric semiconductor materials 10, and the thermal conductivity(κ) of the thermoelectric semiconductor material 17 manufactured fromthe raw thermoelectric semiconductor materials 10 through theabove-described process.

In addition, as shown in FIG. 11, as it is clearly indicated by therelationship between the rotational speed of rotational roll 9 duringmanufacturing slow cooling foils as raw thermoelectric semiconductormaterials 10 and electric conductivity (σ) of manufacturedthermoelectric semiconductor material 17, by using a rotational roll ofthe low rotational speed like the above described value, electricconductivity (σ) of manufactured thermoelectric semiconductor material17 can be increased, compared to the case using raw thermoelectricsemiconductor materials 10 produced by a rotational roll 9 of highrotational speed.

Furthermore, as shown in FIG. 12, as it is clearly indicated from therelationship between the rotational speed of the rotational roll 9during manufacturing the slow cooling foils as raw thermoelectricsemiconductor materials 10 and the Seebeck coefficient (α) ofmanufactured thermoelectric semiconductor material 17, by using arotational roll of the low rotational speed like the above describedvalue, the Seebeck coefficient (α) of manufactured thermoelectricsemiconductor material 17 can be increased, compared to the case usingraw thermoelectric semiconductor materials 10 produced by a rotationalroll 9 of high rotational speed.

Moreover, as shown in FIG. 13, as it is clearly indicated from therelationship between the rotational speed of rotational roll duringmanufacturing slow cooling foils as raw thermoelectric semiconductormaterials 10 and the concentration of the carriers of manufacturedthermoelectric semiconductor material 17, by using a rotational roll ofthe low rotational speed like the above described value, theconcentration of the carriers of manufactured thermoelectricsemiconductor material 17 can be increased, compared to the case usingraw thermoelectric semiconductor materials 10 produced by a rotationalroll 9 of high rotational speed.

Accordingly, as shown in FIG. 14, as it is clearly indicated from therelationship between the rotational speed of the rotational roll 9during manufacturing slow cooling foils as the raw thermoelectricsemiconductor materials 10 and the Figure-of-Merit (Z) of manufacturedthermoelectric semiconductor material 17,

in the thermoelectric semiconductor material 17 manufactured, throughthe above-described procedures, from the raw thermoelectricsemiconductor material 10 that has been manufactured by the rotationalroll 9 of slow speed, the Figure-of-Merit (Z) is increased compared tothe case using the raw thermoelectric semiconductor materials 10produced by a rotational roll 9 of high rotational speed.

Furthermore, as shown in FIG. 4, in the above-described thermoelectricsemiconductor material 17 according to the present invention, thethickness of the slow cooling foils manufactured as raw thermoelectricsemiconductor materials 10 can be increased by slowing the rotationalspeed of rotational roll 9, and thereby the specific surface area can bereduced. As a result, as it is clear from FIG. 15 showing a relationshipbetween the thickness of slow cooling foils as raw thermoelectricsemiconductor materials 10 and the oxygen concentration, measured by aninfrared absorption method, contained in the raw thermoelectricsemiconductor materials 10, oxidization of raw thermoelectricsemiconductor materials 10 can be restricted and the oxygenconcentration in thermoelectric semiconductor material 17 manufacturedfrom the raw thermoelectric semiconductor materials 10 can be reduced.

In addition, as shown in FIG. 5, the width of the slow cooling foilsmanufactured as the raw thermoelectric semiconductor materials 10 can beincreased by slowing the rotational speed of rotational roll 9, andthereby the specific surface area can be reduced. As a result, as it isclear from FIG. 16 showing the relationship between the width of slowcooling foils as raw thermoelectric semiconductor materials 10, and theoxygen concentration, measured by an infrared absorption method,contained in the raw thermoelectric semiconductor materials 10,oxidization of the raw thermoelectric semiconductor materials 10 can berestricted in the same manner as described above, and the oxygenconcentration in manufactured thermoelectric semiconductor material 17can be reduced.

Accordingly, as it is clear from FIG. 17 showing the relationshipbetween the rotational speed of the rotational roll 9 and the oxygenconcentration in thermoelectric semiconductor material 17, the oxygenconcentration contained in manufactured thermoelectric semiconductormaterial 17 can be reduced by slowing the rotational speed of therotational roll 9. Therefore, it is possible to prevent lowering of theelectric conductivity (σ) due to oxidation.

Therefore, as it is clear FIG. 18 showing the relationship between theoxygen concentration in slow cooling foils as raw thermoelectricsemiconductor materials 10, and the Figure-of-Merit, by reducing theoxygen concentration contained in manufactured thermoelectricsemiconductor material 17, the thermoelectric performance of thethermoelectric semiconductor material 17 can be increased.

The electric conductivity (σ) and the Seebeck coefficient (α) of theabove-described manufactured N type thermoelectric semiconductormaterial 17 can be controlled, by adjusting the ratio of Te to Se in theBi₂(Te—Se)₃ based composition, which is the standard for N typethermoelectric semiconductor compositions.

FIG. 19 is a flow chart showing another embodiment of a manufacturingmethod for a thermoelectric semiconductor material of the presentinvention. In this embodiment, in plastically deforming process IVduring the manufacturing procedure of a thermoelectric semiconductormaterial in the same manner as described above, when a compact 12 ispressed, and a shear force is applied in a uniaxial direction parallelto the layering direction of the slow cooling foils of the rawthermoelectric semiconductor materials 10, so that the compact isplastically deformed to a predetermined form, one or more times ofomnidirectional hydrostatic pressure process IV-2 may be carried outduring the process of the uniaxial shear force applying process IV-1 forplastically deforming an object, for example, at the time in which ratioof deformation is low. In the omnidirectional hydrostatic pressureprocess IV-2, during the plastic deformation of the compact 12,deformation of the compact 12 is temporarily restricted by contact withplanes placed in the direction of deformation, and at that state, apressure is continuously applied over a given period of time.

Accordingly, when the above-described omnidirectional hydrostaticpressure process IV-2 is carried out, as shown in FIGS. 20A, 20D, and20C, within a plastic working device 13 having similar configuration asshown in FIGS. 8A, 8B, and 8C, a pair of front and rear restrictingmembers 18, each having approximately parallel surface opposed to eachother intervening a predetermined spacing are provided at positionsbetween restricting members 15 at the lateral sides so as to form aconfiguration in which the space between the above-described restrictingmembers 15 placed in the lateral direction is closed on theanteroposterior sides. When a compact 12 formed in solidificationforming process III is placed in the center portion of the insidebetween the above-described restricting members 15 placed in the lateraldirection so that the layering direction of the raw thermoelectricsemiconductor materials 10 constructing the compact 12 is parallel tothe surfaces of restricting members 15 placed in the lateral direction,a predetermined gap is formed between the above-described compact 12 andfront and rear restricting members 18 so as to provide a space fordeformation of the compact. In addition, a punch 16 a having a planeform corresponding to the space surrounded by the above-describedrestricting members 15 and 18 at lateral and anteroposterior sides, isprovided so as to be moveable in the upward and downward directionswithin the above-described space by a vertical driving unit, not shown.Furthermore, heating units, not shown, are provided at predeterminedpositions on base 14, restricting members 15 and 18, and punch 16 a.Along with preparing a plastic working device 13 a havingabove-described configuration, a plastic working device 13 shown inFIGS. 8A, 8B, and 9C, is also prepared.

When a plastic working process IV is carried out, firstly, as shown inFIGS. 20A and 20B, compact 12 formed in solidification forming processIII is placed in the center portion between restricting members 15placed in the lateral direction in the plastic working device 13 a.After that, temperature conditions and pressure conditions are adjustedas same as in the above-decribed plastically deforming process IV, andpunch 16 a is lowered by the vertical driving unit so that pressure isapplied to the compact 12 from above by the lowering punch 16 a. Then,as shown by two-dot chain lines in FIG. 20A, since the two sides in thedirection of the width of the compact 12 are restricted by restrictingmembers 15 placed in the lateral direction, shear force is applied in auniaxial anteroposterior direction approximately parallel to thelayering direction of the raw thermoelectric semiconductor materials 10forming the compact. As a result, the compact is plastically deformedand flattened in the anteroposterior direction. Thus, a uniaxial shearforce applying process IV-1 is carried out. After that, plasticdeformation continues in the anteroposterior direction, ad thereby, asshown in FIG. 20C, the plastically deformed body of the compact 12 ismade to be contacted with the front and rear restricting members 18. Inthis state, when further pressure is applied from above by the punch 16a, the deformed body of the compact 12 is restricted by the restrictingmembers 15 placed in the lateral direction at two sides in the directionof the width, and also restricted by restricting members 18 at two sidesin the anteroposterior direction, and thereby prevented fromdeformation. Therefore, pressure provided by the punch 16 a is appliedto the deformed body of the compact 12 as omnidirectional hydrostaticpressure. As described above, the omnidirectional hydrostatic pressureprocess IV-2 is carried out.

After that, the plastically deformed body of compact 12 which has beenexpanded (plastically deformed) in the anteroposterior direction untilit contacts front and rear restricting members 18, is taken out from theplastic working device 13 a, and the plastically deformed body of thecompact 12 is placed in the center portion between restricting members15 placed in the lateral direction of plastic working device 13 in thesame manner as described in reference to FIGS. 8A, 8B, and 8C. Afterthat, punch 16 is lowered so as to press further the plasticallydeformed body of the above-described compact 12 from above, and thereby,the plastically deformed body of the compact 12 is further expanded byapplying a shear force in the anteroposterior direction, which is anuniaxial direction approximately parallel to the layering direction ofraw thermoelectric semiconductor materials 10 constructing the compact12 before plastic deformation. Thus, the uniaxial shear force applyingprocess IV-1 is carried out, and thermoelectric semiconductor material17 is manufactured.

The above-described omnidirectional hydrostatic pressure process IV-2may be carried out two or more times. In this case a plurality ofplastic working devices 13 a, in which the distance between front andrear restricting members 18 increases step by step, are prepared and thedevices are sequentially used from the one having smallest distancebetween front and rear restricting members 18 is the smallest to the onehaving the largest distance between front and rear restricting members18. Pressure is applied to the compact 12 formed in solidificationforming process III from above by lowering the punch 16 a in the samemanner as described above, and thus, a shear force is applied in auniaxial direction approximately parallel to the layering direction ofraw thermoelectric semiconductor materials 10. As a result, the compactis plastically deformed so that the amount of deformation from theinitial state sequentially increases. After that, omnidirectionalhydrostatic pressure is applied in a state in which deformation isrestricted by front and rear restricting members 18, and finally, thecompact may be plastically deformed so as to expand in theanteroposterior direction by the plastic working device 13 not havingthe front and rear restricting members 18.

In this case, by caring out the above-described omnidirectionalhydrostatic pressure process IV-2 on a compact 12 during plasticdeformation in the uniaxial shear force applying process IV-1, thedensity of the above-described compact 12 during plastic deformation canbe increased. Therefore, a possibility of occurrence of buckling isprevented in the compact 12 on which the plastically deforming processis finally cared out in the plastic working device 13. In addition, twoend portions of the compact 12 in the anteroposterior direction, whichare the end portions in the direction of plastic deformation, arepressed against front and rear restricting members 18, and thereby, theforms of the two end pons in the anteroposterior direction, of thecompact 12 are adjusted at a stage during plastic deformation. Thus, thedeformation rate of the compact 12 can be made uniform, and therefore,it is possible to enhance the homogeneity of the texture of manufacturedthermoelectric semiconductor material 17.

When the omnidirectional hydrostatic pressure process IV-2 is carriedout, due to the contact of the end portions of the compact 12 in theanteroposterior direction with front and rear restricting members 18,there is a possibility that the orientation of C face of crystal grains11 may be slightly disordered in the end portions of the compact 12 inthe anteroposterior direction. Whereas, finally in plastic workingdevice 13, a shear force is applied in a uniaxial directionapproximately parallel to the layering direction of raw thermoelectricsemiconductor material 10 constructing the compact 12 so that thecompact is expanded without restriction in the anteroposteriordirection.

Therefore, it is possible to uniformly align the direction of C face andthe direction of c-axis of crystal grains 11 even in the end portions inthe anteroposterior direction of manufactured thermoelectricsemiconductor material 17.

Furthermore, in a manufacturing method for a thermoelectricsemiconductor material of the present invention, as shown in FIG. 19, astress stain processing process V is provided as the process after theabove-described plastically deforming process IV. In the stress strainprocessing process V, the thermoelectric semiconductor material 17,manufactured and plastically deformed into a predetermined form inplastically deforming process IV may be maintained at a predeterminedtemperature, for example at a temperature from 350° C. to 500° C., for apredetermined period of time, for example, for 30 minutes to 24 hours sothat dislocations or vacancies of crystal lattice are reduced orreconstructed as a result of heat treatment. As a result, stress strainwhich is generated as a result of the plastic deformation in theplastically deforming process IV and remains in the structure ofthermoelectric semiconductor material 17 may be eliminated. It is clearthat the same effects can be obtained in the stress strain processingprocess V even when the temperature condition is maintained for 24 hoursor more.

Moreover, a defect concentration controlling process VII may be providedas the process after the above-described stress strain processingprocess VI. By holding the thermoelectric semiconductor material 17,from which residual stress strain has been removed in theabove-described stress strain processing process VI, at a predeterminedtemperature for a predetermined period of time in the defectconcentration controlling process VII, the concentration of defects inthe thermoelectric semiconductor material 17 may be changed, andtherefore, the electric conductivity (σ) and the Seebeck coefficient (α)may be controlled.

The thermoelectric semiconductor material 17 manufactured in theplastically deforming process IV retains a stricture of rawthermoelectric semiconductor materials 10 constructing the compact 12,namely Bi₂(Te—Se)₃ based complex compound semiconductor including heterophases (Te rich phases) in the crystal grains or in the grainboundaries. Since the excess Te is a component of the Bi₂(Te—Se)₃ basedthermoelectric semiconductor, when the above-described thermoelectricsemiconductor material 17 is heat treated, the excess Te reacts with themain component of Bi₂(Te—Se)₃ based semiconductor, and fill in thedefects of the main component. When a slight amount of dopant such as Agis introduced in the main component, performance changes largely. Suchdopant has a large influence even when it is distributed in the grainboundaries. Performance may change largely, if the dopant diffuse intothe main component portion by the use at a high temperature or by a heattreatment. It is considered that the change in the concentration ofdefects in thermoelectric semiconductor material 17 due to the excess Tecan provide effects which cancel or accelerate the effects of thedopant.

Next, as manufacturing method for a thermoelectric semiconductor elementaccording to the present invention, a case in which N typethermoelectric semiconductor element 3 a is manufactured using N typethermoelectric semiconductor material 17 manufactured in accordance withthe embodiments shown in FIGS. 1 to 18 is described in the following.

In this case, in the N type thermoelectric semiconductor material 17,the extending direction of C face and the direction of c-axis of thehexagonal structure of crystal grains 11 are uniformly alignedthroughout the entire structure. Therefore, considering the orientationof crystal grains 11 having uniform orientation, thermoelectricsemiconductor element 3 a is formed by being cut out from the material,so that the direction in which a current and heat are conveyed can beset in the extending direction of C face in the hexagonal structure ofcrystal 11.

In the N type thermoelectric semiconductor material 17, as shown in FIG.9B, C face of the hexagonal structure in each crystal grain extends inthe direction of expansion of the compact 12 during plastic deformation(direction of arrow t), and c-axis is oriented approximately in thedirection of pressure (direction of arrow p) during the plasticdeformation. Therefore, first as shown in the upper portion of FIG. 21,at predetermined spacing position in the direction of expansion of thecompact 12 during the plastic deformation (direction of arrow t), thethermoelectric semiconductor material 17 is sliced along a planeperpendicular to the direction of expansion, and a wafer 19 is cut out,as shown in the middle of FIG. 21.

As a result, C face of the hexagonal structure of crystal grains 11 isoriented in the direction of the thickness of the above-described wafer19.

Next, a conductive material processed surfaces 20 are formed byprocessing the both ends of the wafer 19, for example, by a platingprocess by a plating device, not shown. Subsequently, as shown bytwo-dot chain lines in the middle portion of FIG. 21, the wafer 19processed with conductive material is cut along two planes: a planeperpendicular to the direction (direction of arrow p) in which compact12 is pressed during the manufacture of the thermoelectric semiconductormaterial 17; and a plane defined by two axes of the direction ofpressing (direction of arrow p) and the direction of expansion(direction of arrow t) during the manufacture of the thermoelectricsemiconductor material 17. Thus, a rectangular solid form, as shown inthe lower portion of FIG. 21 is cut out (diced), and thereby the N typethermoelectric semiconductor element 3 a is manufactured.

As a result, the above-described N type thermoelectric semiconductorelement 3 a has a crystal structure in which, as shown in the lowerportion of FIG. 21, C face of the hexagonal structure of crystal grains11 extends throughout long length in the direction (as shown by arrow tin the figure, the same direction as the direction of expansion of thethermoelectric semiconductor material 17 during the manufacture) of apair of opposing surfaces 20 which are processed with a conductivematerial. The pair of the surface 20 correspond to conductive materialprocessed surfaces 20 of the wafer 19 processed with a conductivematerial. In addition, c-axes of crystal grains 11 extend in thedirection of pressing (direction of arrow p in the figure) during themanufacture of the thermoelectric semiconductor material 17 among thetwo axial directions perpendicular to the conductive material processedsurface 20.

Accordingly, by attaching a metal electrode (not shown) to theabove-described conductive material processed surface 20, an N typethermoelectric semiconductor element 3 a having excellent thermoelectricperformance can be obtained, by making the element to have a textualstructure in which the direction of c-axis, as well as the direction ofC face of the hexagonal structure of the crystal grains 11 are uniformlyoriented, and allowing the current and heat to be applied in thedirection of C face of the hexagonal structure of the above-describedcrystal grains 11.

Next, a case in which a P type thermoelectric semiconductor material ismanufactured is described. In this case, to prepare a stoichiometriccomposition of a raw alloy of an P type thermoelectric semiconductor ina component mixing process I shown in FIG. 1, Bi, Sb and Te are weighedso that the raw alloy contains 7 to 10 atomic % of Bi, 30 to 33 atomic %of Sb, and 60 atomic % of Te. The weighed metals are mixed to obtain a(Bi—Se)₂ Te₃ based composition. Furthermore an excess Te is aided sothat 0.1 to 5% by weight of Te is contained in the entire (Bi—Se)₂ Te₃based component, and thus an alloy having excess Te is prepared. At thattime, a predetermined amount of dopant for forming a P typethermoelectric semiconductor, such as Ag or Pb may be added.

Subsequently, in the same manner as in the case for manufacturingabove-described N type thermoelectric semiconductor material 17, in slowcooling foil manufacturing process II using a device shown in FIG. 2,molten alloy 8 of the metal mixture that has been mixed in theabove-described component preparing process I is supplied from a nozzleof melting crucible 6, having a diameter of 0.5 mm to a surface ofrotational roll 9 slowly rotating at a circumferential velocity of 5m/sec or less, preferably at a circumferential velocity of 2 m/sec orless, so as to be slowly cooled and solidified, and thereby, plateshaped raw thermoelectric semiconductor materials 10 (slow cooling foil)are manufactured.

The circumferential velocity of rotational roll 9 is set at 5 m/sec orless, preferably 2 m/sec or less. By using such velocity, in the samemanner as in the case for forming the N type raw thermoelectricsemiconductor material 10, the slow cooling foils are manufactured tohave a thick thickness of 30 μm or more, preferably, the slow coolingfoils are formed to have a thickness of no less than 70 μm, and thereby,raw thermoelectric semiconductor materials 10 having an excellentcrystalline orientation and large crystal grains 11 extending throughoutalmost entire plate thickness can be obtained. At the same time, thewidths of the slow cooling foils manufactured as raw thermoelectricsemiconductor material 10, are increased, the volume of a single pieceof the raw thermoelectric semiconductor material 10 is increased, andthereby the specific surface area of the piece can be reduced.

As a result, in the same manner as the above-described N type rawthermoelectric semiconductor material 10, when the P type rawthermoelectric semiconductor material 10 is cooled on rotational roll 9,the crystal structures of the complex compound semiconductor phases ofBi₂Te₃ and Sb₂Te₃ are respectively solidified and crystallized, in whichcrystalline orientation is aligned in the direction of the platethickness. At the same time, Te rich phases including excess Te in thecomposition of Bi₂Te₃ or Sb₂Te₃ are microscopically dispersed as anon-amorphous separated phase in the crystal grains and grain boundariesof the Hive complex compound semiconductor phases of Bi₂Te₃ and Sb₂Te₃.Thus a raw thermoelectric semiconductor material 10 that is thought tohave a structure having crystal strain by precipitation of hetero phase(Te-rich phase) or by nucleation of hetero phase nuclei within crystalgrains and grain boundaries of the (Bi—Sb)₂Te₃ based complex compoundsemiconductor, can be achieved. In this raw thermoelectric semiconductormaterial 10, in the same manner as that shown in FIG. 3, crystal grains11 extend in approximately the direction of the plate thickness, and thecrystal grains have a length almost corresponding to the platethickness. Powder particles may be removed in advance by sieving fromthe raw thermoelectric semiconductor materials, before the followingsolidification forming process III.

Subsequently, in solidification forming process III, slow cooling foilsof P type raw thermoelectric semiconductor materials 10 manufactured inthe slow cooling foil manufacturing process II, are layered in thedirection approximately parallel to the direction of the platethickness, and are packed in a mold, not shown. After that, the layeredbody is sintered under the same pressure and temperature conditions by amultistage heating method in the same manner as the manufacturingprocess of compact 12 having the N type composition. As a result, thelayered raw thermoelectric semiconductor materials 10 are plasticallyworked, solidified and formed so that the respective pieces of rawthermoelectric semiconductor materials 10 are made to make contact witheach other and the interstices between the raw thermoelectricsemiconductor materials are eliminated. Thus, a compact 12 inrectangular solid form in the same manner as those shown in FIGS. 7A,7B, and 7C is manufactured.

As a result, no or only little limited amount of Te rich phases whichhave been formed in the P type raw thermoelectric semiconductor material10 are converted to liquid phases during sintering. Therefore, thecompact 12 is formed maintain a structure comprising complex compoundsemiconductor phases having the composition of Bi₂Te₃ and Sb₂Te₃microscopically dispersing Te rich phases containing excess Te in theabove-described compositions.

Subsequently, in a plastically deforming process IV, in the same manneras in the case for manufacturing the N type thermoelectric semiconductormaterial 17, using a plastic working device 13 as shown in FIGS. 8A, 8B,8C, and 8D, along with hating the compact 12 at a temperature no higherthan 500° C., preferably, no higher than 350° C., the compact isplastically deformed so as to expand in a uniaxial directionapproximately parallel to the layering direction of the rawthermoelectric semiconductor materials 10, and thereby, P typethermoelectric semiconductor material 17 is manufactured. Theabove-described temperature condition for heating is varied depending onthe excessive amount of Te, and the processing temperate is increasedwith decreasing amount of excess Te.

As a result, by applying shear force only in the layering direction ofraw thermoelectric semiconductor materials 10, in the same manner asthose shown in FIGS. 9A and 9B, crystal grains 11 oriented in thedirection of the plate thickness of the raw thermoelectric semiconductormaterial 10 in the compact 12 are plastically deformed so as to beflatted in the uniaxial direction in which the shear force is applied.In addition, the cleavage planes are oriented so as to be approximatelyperpendicular to the direction in which pressure is applied, and thecompact is deformed so that C face of the hexagonal structure of eachcrystal grain 11 is extended in the direction of expansion (direction ofarrow t in FIGS. 9A and 9B). At the same time, a P type thermoelectricsemiconductor material 17 in which c-axes of most of crystal grains 11are oriented in the direction of compression (direction of arrow p inFIGS. 9A and 9B) during the plastic deformation is formed.

Accordingly, in the P type thermoelectric semiconductor material 17,crystal strain is generated by the presence of the hetero phase withincrystal grains and grain boundaries, as well as by the presence of grainboundaries. By the generation of the crystal strain, thermalconductivity (1 c) can be reduced. In addition, since the directions ofc-axes and extending directions of C face of the hexagonal structure ofthe crystal grains 11 are approximately uniformly oriented,thermoelectric performance (of which the Figure-of-Merit is Z) can beenhanced by setting the direction for conveying a current and heat tothe extending direction of C face of the crystal grains 11.

Moreover, since the P type raw thermoelectric semiconductor material 10is manufactured to have a large thickness and a large width, andtherefore, have a small specific surface area, and is solidified andformed to manufacture P type thermoelectric semiconductor material 17,the oxygen concentration contained in the thermoelectric semiconductormaterial 17 can be reduced. Thus, a reduction in the electricconductivity (σ) due to oxidation can be prevented. By this reduction,an the thermoelectric performance of thermoelectric semiconductormaterial 17 can also be improved.

The electric conductivity (σ) and the Seebeck coefficient (α) of the Ptype thermoelectric semiconductor material 17 can be controlled byadjusting the amounts of Bi and Sb in the (Bi—Sb)₂Te₃ based composition,which is the standard of the composition of P type semiconductors. Inaddition, during the manufacturing process of the P type thermoelectricsemiconductor material 17, omnidirectional hydrostatic pressure processIV-2 in plastically deforming process IV shown in FIG. 19 may be carriedout. In addition, stress stain processing process V and defectconcentration controlling process VI may be carried out as a postprocess of the plastically deforming process IV.

Next, a case in which P type thermoelectric semiconductor element 2 a ismanufactured using the P type thermoelectric semiconductor material 17manufactured by the above-described method is described.

In this case, also in the above-described P type thermoelectricsemiconductor material 17, in the same manner as N type thermoelectricsemiconductor material 17 shown in FIGS. 9A and 9B, throughout entiretextual structure, C face of the hexagonal structure of most of crystalgrains 11 extend in the direction of expansion of the compact 12 duringthe plastic deformation (direction of arrow t in FIGS. 9A and 9B), andthe c-axes are almost oriented in the direction of the pressure duringthe plastic deformation (direction of arrow p in FIGS. 9A and 9B).Therefore, in the same manner as in manufacturing method for N typethermoelectric semiconductor element 3 a shown in FIG. 21, firstly, asshown in the upper portion of FIG. 21, at predetermined spacing positionin the direction of expansion of the compact 12 during the plasticdeformation (direction of arrow t), the thermoelectric semiconductormaterial 17 is sliced along a plane perpendicular to the direction ofexpansion, and thereby a wafer 19 is cut out, as shown in the middle ofFIG. 21. After that conductive material processed surfaces 20 are formedby processing both end surfaces in the direction of thickness of thewafer 19 with conductive material. Subsequently, by cutting the wafer19, a P type thermoelectric semiconductor element 2 a of a rectangularsolid form can be manufactured in the same manner as the N typethermoelectric semiconductor element 3 a shown in the lower portion ofFIG. 21.

As a result, the P type thermoelectric semiconductor element 2 a has, inthe same manner as the above-described N type thermoelectricsemiconductor element 3 a, a crystal structure in which C face of thehexagonal structure of crystal grains 11 extends throughout long lengthin the direction of a pair of opposing surface 20 which are processedwith a conductive material. In addition, c-axes of crystal grains 11extend in the direction of pressing (direction of arrow p) during themanufacture of the thermoelectric semiconductor material 17 among thetwo axial directions perpendicular to the conductive material processedsurface 20. Therefore the P type thermoelectric semiconductor elementhas an excellent thermoelectric performance.

As another embodiment of the present invention, a thermoelectric modulethat uses P type and N type thermoelectric semiconductor elements 2 aand 3 a that have been manufacture in accordance with theabove-described method of the present invention, and manufacturingmethod of the thermoelectric module are described.

FIG. 22 shows thermoelectric module 1 a of the present invention, whichcomprises a PN element pair as in the same manner as a conventionalthermoelectric module 1 shown in FIG. 27. In the formation of the PNelement pair, the P type thermoelectric semiconductor element 2 a and Ntype thermoelectric semiconductor element 3 a respectively manufacturedby the method of the present invention are arranged so that the elementsare aligned in the direction perpendicular both to the extendingdirection of C face and the direction of c-axis of hexagonal structureof the crystal grains 11. Conductive material processed surfaces of thethermoelectric semiconductor elements 2 a and 3 a opposed to each otherin the extending direction of C face of the crystal grains are joinedvia a metal electrode 4.

As a result, in the above-described thermoelectric module 1 a of thepresent invention, current and heat can be conveyed in the extendingdirection of C face of the crystal grains 11 of the P typethermoelectric semiconductor element 2 a and N type thermoelectricsemiconductor element 3 a, in which the extending direction of C faceand the direction of c-axis of crystal gains 11 are approximatelyuniformly oriented. Therefore, thermoelectric module 1 a having anexcellent thermoelectric performance can be achieved.

In addition, when thermoelectric cooling, thermoelectric heating,thermoelectric power generation, and the like are carried out using theabove-described thermoelectric module 1 a, expansion or contraction ofthe metal electrode 4 accompany temperature deviation. Therefore, toadjacent P type and N type thermoelectric semiconductor elements 2 a and3 a joined via a metal electrode 4, stress is applied in the directionin which the elements come close to each other, or move away from eachother. While in the above-described thermoelectric module, when a PNelement pair is formed as shown in FIG. 22, adjacent thermoelectricsemiconductor elements 2 a and 3 a joined via a metal electrode 4 arearranged in the same plane as the direction of C face of crystal grains11. Terefore, stress caused by expansion or contraction of the metalelectrode 4 can be applied to respective crystal grains 11 only in thedirection parallel to C plan. Accordingly, even when the stress isapplied, interlayer peeling of the crystal grains 11 in the hexagonalstructure in the respective structures of thermoelectric semiconductorelements 2 a and 3 a can be prevented, and thus, the damage to thethermoelectric semiconductor elements 2 a and 3 a due to cleavage can beprevented, and therefore, strength and durability of the themthermoelectric module 1 a can be enhanced. When a PN elemental pair isformed, as a comparative example as shown in FIG. 23, by aligning the Ptype and N type thermoelectric semiconductor elements 2 a and 3 a in thedirection of c-axis in the hexagonal structure of crystal grains 11; andjoining respective thermoelectric semiconductor elements 2 a and 3 a viametal electrode 4, the caused by expanding or contracting deformation ofthe metal electrode 4 due to thermal deviation is applied respectivelyto the thermoelectric semiconductor elements 2 a and 3 a in thedirection of c-axes of crystal grains 11. Accordingly, the stress worksto peel the layers in the hexagonal structure of these crystal grains11. In such a case, the damage to thermoelectric semiconductor elements2 a and 3 a due to cleavage may be easily occur. Such occurrence ofdamage can be prevented in the above-described thermoelectric module 1 aof the present invention.

The present invention is not limited only to the above-describedembodiments. In the solidification forming process III in themanufacturing method for a thermoelectric semiconductor material, theabove description shows a processing condition for solidifying andforming (sintering) the raw thermoelectric semiconductor material 10 ata temperature no lower than 380° C. and no higher than 500° C.,preferably, a no lower than 420° C. and no higher than 450° C., ismaintained for 5 seconds to 5 minutes. While, it is also possible tosinter raw thermoelectric semiconductor materials 10 for a long periodof time at a temperature no higher than 400° C.

When temperature conditions and heating time may be set so thatsegregation, dropping of separated phase, and liquid phaseprecipitation, or the like of the Te rich phases having a low meltingpoint and are dispersed in complex compound semiconductor phases do notcompletely occur, it is possible to form a compact 12 through plasticdeformation by applying pressure, rolling, or by extrusion. As aplastically processing device 13 used in plastically deforming processTV, a structure having a punch 16 which can be raised and lowered insidebetween restricting members 15 placed in the lateral direction isdescribed. In this case, the compact 12 is placed in the middle portioninside the restricting members 15 placed in the lateral direction, andthis compact 12 is pressed from above by punch 16, and thereby, theabove-described compact 12 is expanded toward the two anteroposteriorsides in a uniaxial direction parallel to the layering direction of rawthermoelectric semiconductor material 10. While, as shown in FIGS. 24Aand 24B, the plastically working device 13 may have a configuration inwhich an additional restricting member 15 b is provided in a position onone side of the base 14 between restricting members 15 placed in thelateral direction to restrict the deformation (expansion) of compact 12in forward and backward direction in one direction. In this case, whencompact 12 is plastically deformed, compact 12 is firstly placed so asto be contacted with the restricting members 15 placed in the lateraldirection and the restricting member 15 b. Subsequently, the compact 12is pressed from above by punch 16 as shown by two-dot chain lines in theupper portion of FIG. 21. As a result, the compact 12 is expanded onlyin one direction opposite to the restricting member 15 b. Plasticallyworking device 13 a used in omnidirectional hydrostatic pressure processIV-2 shown in FIGS. 20A, 20B, and 20C may be provided with a fixingposition ring 15 a same as that shown in FIG. 8D, on the outer peripheryof restricting members 15 placed in the lateral direction and front andrear restricting members 18. In this case, during the plasticdeformation of the compact 12, stress applied in the direction to theoutside of the above-described restricting members 15 and 18 is receivedby the fixing position ring. When omnidirectional hydrostatic pressureprocess IV-2 is carried out two or more times, instead of preparing aplurality of plastically working device 13 a having different spacingbetween front and rear restricting members 18, it is also possible touse a plastic working device 13 a in which positions of front and rearrestricting members 18 may be set to have selective spacing. While acomposition of raw alloy for thermoelectric semiconductors is, in eithercase of P type or N type, described to have excess Te added tostoichiometric composition of the thermoelectric semiconductor complexcompound, it is also possible to add as excess composition, any elementselected from Bi, Se, and Sb element instead of Te to the stoichiometriccomposition of the thermoelectric semiconductor complex compound. Amanufacturing method for a thermoelectric semiconductor material, athermoelectric semiconductor element, and a thermoelectric moduleaccording to the present invention may be applied to the raw alloyhaving the stoichiometric composition of the thermoelectricsemiconductor complex compound to which an excess Te is not added. Inthis case, improvement of thermoelectric performance can be expected dueto an improvement of orientation of crystal grains 11 in the texture ofthermoelectric semiconductor material 17. While Bi₂(Te—Se)₃ based, threeelement based composition was described as a stoichiometric compositionof raw alloy for N type thermoelectric semiconductor, it is alsopossible to apply a manufacturing method for a thermoelectricsemiconductor material, a thermoelectric semiconductor element, or athermoelectric module to a raw alloy having a Bi₂Te₃ based, two elementbased, stoichiometric composition or a four element based stoichiometriccomposition comprising (Bi—Sb)₂Te₃ based composition added with smallamount of Se. While (Bi—Sb)₂Te₃ based, three element based compositionwas described as a stoichiometric composition of P type thermoelectricsemiconductor complex compound, it is also possible to apply amanufacturing method for a thermoelectric semiconductor material, athermoelectric semiconductor element, or a thermoelectric module to araw alloy having a four element based stoichiometric compositioncomprising Bi₂(Te—Se)₃ based composition added with small amount of Sb.In the above description, plastically working device 13 and 13 a areused when a thermoelectric semiconductor material 17 is manufacturedthrough plastic deformation by applying a shear force to a compact 12 inwhich slow cooling foils of raw thermoelectric semiconductor materials10 are layered in the direction of the plate thickness and aresolidified and formed, in a uniaxial direction approximately parallel tothe layering direction of the above-described thermoelectricsemiconductor element 10. A high pressure pressing device 21 with a pairof dies 22 that are moveable in the direction in which they come closeto each other or they move away from each other as shown in FIG. 25A, ora rolling device 23 provide with a roller 24 as shown in FIG. 25B may beused to press the compact 12 in a uniaxial direction perpendicular tothe layering direction while moving the compact in the main layering donof raw thermoelectric semiconductor materials 10. In this case, since afriction is applied in the direction perpendicular to both the layeringdirection of the raw thermoelectric semiconductor material 10 and thedirection of pressure application, the compact is not spread or even ifit spreads, amount of deformation is limited to small value. Therefore,restricting members are not specifically required. Of course, a varietyof modifications can be applied to the embodiments within the scope thatdoes not deviate from the gist of the present invention.

EXAMPLE

A thermoelectric module 1 a was manufactured by forming a PN elementpair of P type and N type thermoelectric semiconductor elements 2 a and3 a manufactured by a manufacturing method for a thermoelectricsemiconductor element of the present invention. The thermoelectricperformance of the module was compared with that of a thermoelectricmodule manufactured in accordance with another method.

As a result, the Figure-of-Merit, shown by solid circle ● and opencircle o in FIG. 26, were obtained as the thermoelectric performance ofthermoelectric module 1 a manufactured in accordance with the presentinvention.

The result indicates, it was found that high thermoelectric performanceis gained according to the invention.

As a result, thermoelectric module of the present invention indicateshigh thermoelectric performance in comparison with a case in which a Ptype thermoelectric semiconductor element and an N type thermoelectricsemiconductor element are both manufactured only by conventional hotpressing of a raw thermoelectric semiconductor material according (shownby open triangle A in FIG. 26), and a case in which N typethermoelectric semiconductor element 2 a is manufactured by amanufacturing method for a thermoelectric semiconductor element of thepresent invention, while a P type thermoelectric semiconductor elementis manufactured only by hot pressing of a raw thermoelectricsemiconductor material (shown by open diamond ⋄ and solid diamond ♦ inFIG. 26).

1. A thermoelectric semiconductor material produced by: layering and packing plate shaped raw thermoelectric semiconductor materials made of a raw alloy having a predetermined composition of a thermoelectric semiconductor to form a layered body; solidifying and forming the layered body to form a compact; applying pressure to the compact in a uniaxial direction that is perpendicular or nearly perpendicular to a main layering direction of the raw thermoelectric semiconductor materials; and thereby applying a shear force in a axial direction that is approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials; and plastically deforming the compact.
 2. A thermoelectric semiconductor material having a compound phase comprising: complex compound semiconductor phase having a predetermined stoichiometric composition of a compound thermoelectric semiconductor, and a Te rich phase in which excess Te is added to the stoichiometric composition.
 3. A thermoelectric semiconductor material produced by: adding excess Te to a predetermined stoichiometric composition of a compound thermoelectric semiconductor to form a raw alloy; layering and packing plate shaped raw thermoelectric semiconductor materials made of the raw alloy to form a layered body; solidifying and forming the layered body to form a compact; applying pressure to the compact in an axial direction perpendicular or nearly perpendicular to a main layering direction of the raw thermoelectric semiconductor materials; and thereby applying shear force in an axial direction approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials; and plastically deforming the compact.
 4. The thermoelectric semiconductor material according to claim 2, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a (Bi—Sb)₂Te₃ based composition.
 5. The thermoelectric semiconductor material according to claim 3, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a (Bi—Sb)₂Te₃ based composition.
 6. The thermoelectric semiconductor material according to claim 2, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a Bi₂(Te—Se)₃ based composition.
 7. The thermoelectric semiconductor material according to claim 3, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a Bi₂(Te—Se)₃ based composition.
 8. A thermoelectric semiconductor element produced by: layering and packing plate shaped raw thermoelectric semiconductor materials made of a raw alloy having a predetermined composition of a thermoelectric semiconductor to form a layered body; solidifying and forming the layered body to form a compact; applying pressure to the compact in an axial direction perpendicular or approximately perpendicular to a main layering direction of the raw thermoelectric semiconductor materials; and thereby applying shear force in an axial direction approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials; and plastically deforming the compact to form a thermoelectric semiconductor material; cutting out a thermoelectric semiconductor element from the thermoelectric semiconductor material so that a plane approximately perpendicular to the uniaxial direction in which the shear force is applied during the plastic deformation of the compact can be used as a contact surface with an electrode.
 9. The thermoelectric semiconductor element according to claim 8 wherein the plate shaped raw thermoelectric semiconductor material have a compound phase comprising: a complex compound semiconductor phase having a predetermined stoichiometric composition of a compound thermoelectric semiconductor; and a Te rich phase including excess Te in the stoichiometric composition.
 10. The thermoelectric semiconductor element according to claim 9, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a (Bi—Sb)₂Te₃ based composition.
 11. The thermoelectric semiconductor element according to claim 9, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a Bi₂(Te—Se)₃ based composition.
 12. A thermoelectric module comprising a PN element pair produced by: layering and packing respectively plate shaped raw thermoelectric semiconductor materials made of a raw alloy comprising a composition of P type thermoelectric semiconductor, and plate shaped raw thermoelectric semiconductor materials made of a raw alloy comprising a composition of N type thermoelectric semiconductor to form layered bodies; solidifying and forming the layered bodies to form compacts; applying pressure to the compacts having the compositions of P type and N type thermoelectric semiconductor in an axial direction perpendicular or approximately perpendicular to a main layering direction of the raw thermoelectric semiconductor materials; and thereby applying shear force in an axial direction approximately parallel to the main layer direction of the raw thermoelectric semiconductor materials; and plastically deforming the compacts to form P type and N type thermoelectric semiconductor materials; cutting out P type and N type thermoelectric semiconductor elements from the P type and N type thermoelectric semiconductor materials so that planes approximately perpendicular to the uniaxial direction in which the shear force is applied during the plastic deformation of the compacts can be used as contact surfaces with an electrode; arranging the P type and N type thermoelectric semiconductor elements so that the elements are aligned in the direction perpendicular to the axial direction of pressure application during plastic deformation of the compacts, and also perpendicular to the direction of shear force by the pressure application; joining the P type and N type elements via a metal electrode.
 13. The thermoelectric module according to claim 12, wherein the plate shaped P type and N type raw thermoelectric semiconductor materials respectively have a compound phase comprising: complex compound semiconductor phase having a predetermined stoichiometric composition of a compound thermoelectric semiconductor; and a Te rich phase in which excess Te is added to the stoichiometric composition.
 14. The thermoelectric module according to claim 13, wherein the stoichiometric composition of the P type compound thermoelectric semiconductor is a (Bi—Sb)₂Te₃ based composition.
 15. A thermoelectric module according to claim 13, wherein the stoichiometric composition of the N type compound thermoelectric semiconductor is a Bi₂(Te—Se)₃ based composition.
 16. A manufacturing method for a thermoelectric semiconductor material comprising: melting a raw alloy having a predetermined composition of a thermoelectric semiconductor; having the raw alloy to be contacted with a surface of a cooling member to form plate shaped raw thermoelectric semiconductor materials; layering and packing the plate shaped raw thermoelectric semiconductor materials to form a layered body; solidifying and forming the layered body to form a compact; applying pressure to the compact in one of two axial directions which are crossing each other in a plane approximately perpendicular to the main layering direction of the raw thermoelectric semiconductor materials, while preventing deformation of the compact in the other axial direction; and thereby applying shear force in an axial direction approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials; and plastically deforming the compact to form a thermoelectric semiconductor material.
 17. The manufacturing method for a thermoelectric semiconductor material according to claim 16, wherein the raw alloy has a composition in which excess Te is added to a predetermined stoichiometric composition of a compound thermoelectric semiconductor.
 18. The manufacturing method for a thermoelectric semiconductor material according to claim 17, wherein the raw alloy comprises a composition in which 0.1 to 5% of excess Te is added to the stoichiometric composition of a compound thermoelectric semiconductor comprising 7 to 10 atomic % of Bi, 30 to 33 atomic % of Sb, and 60 atomic % of Te.
 19. The manufacturing method for a thermoelectric semiconductor material according to claim 17, wherein the raw alloy comprises a composition in which 0.01 to 10% of excess Te is added to the stoichiometric composition of a compound thermoelectric semiconductor comprising 40 atomic % of Bi, 50 to 59 atomic % of Te, and 1 to 10 atomic % of Se.
 20. The manufacturing method for a thermoelectric semiconductor material according to claim 17, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 21. The manufacturing method for a thermoelectric semiconductor material according to claim 18, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; thing the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 22. The manufacturing method for a thermoelectric semiconductor material according to claim 19, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by along with applying pressure; heating the raw material at a temperate no lower dm 380° C. and no higher than 500° C.
 23. The manufacturing method for a thermoelectric semiconductor material according to claim 16, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 24. The manufacturing method for a thermoelectric semiconductor material according to claim 17, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 25. The manufacturing method for a thermoelectric semiconductor material according to claim 18, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 26. The manufacturing method for a thermoelectric semiconductor material according to claim 19, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 27. The manufacturing method for a thermoelectric semiconductor material according to claim 20, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 28. The manufacturing method for a thermoelectric semiconductor material according to claim 21, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 29. The manufacturing method for a thermoelectric semiconductor material according to claim 22, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 30. The manufacturing method for a thermoelectric semiconductor material according to claim 16, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 31. The manufacturing method for a thermoelectric semiconductor material according to claim 17, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 32. The manufacturing method for a thermoelectric semiconductor material according to claim 18, when a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 33. The manufacturing method for a thermoelectric semiconductor material according to claim 19, why a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 34. The manufacturing method for a thermoelectric semiconductor material according to claim 20, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 35. The manufacturing method for a thermoelectric semiconductor material according to claim 21, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 36. The manufacturing method for a thermoelectric semiconductor material according to claim 22, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 37. A manufacturing method for a thermoelectric semiconductor element, comprising: melting a raw alloy having a predetermined composition of a thermoelectric semiconductor; having the raw alloy to be contacted with a surface of a cooling member to form plate shaped raw thermoelectric semiconductor materials; layering and packing in approximately layered form the plate shaped raw thermoelectric semiconductor materials to form a layered body; solidifying and forming the layered body to form a compact; applying presume to the compact in one of two axial directions which are crossing each other in a plane approximately perpendicular to the main layering direction of the raw thermoelectric semiconductor materials, while preventing deformation of the compact in the other axial direction; and thereby applying shear force in an axial direction approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials; and plastically deforming the compact to form a thermoelectric semiconductor material; and cutting out a thermoelectric semiconductor element from the thermoelectric semiconductor material so that a plane approximately perpendicular to the uniaxial direction in which the shear force is applied during the plastic deformation of the compact can be used as a contact surface with an electrode.
 38. The manufacturing method for a thermoelectric semiconductor element according to claim 37, wherein the raw alloy has a composition in which excess Te is added to a predetermined stoichiometric composition of a compound thermoelectric semiconductor.
 39. The manufacturing method for a thermoelectric semiconductor element according to claim 38, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a (Bi—Sb)₂Te₃ based composition.
 40. The manufacturing method for a thermoelectric semiconductor element according to claim 39, when in the raw alloy comprises a composition in which 0.1 to 5% of excess Te is added to the stoichiometric composition of a compound thermoelectric semiconductor comprising 7 to 10 atomic % of Bi, 30 to 33 atomic % of Sb, and 60 atomic % of Te.
 41. The manufacturing for a thermoelectric semiconductor element according to claim 38, wherein the stoichiometric composition of the compound thermoelectric semiconductor is a Bi₂(Te—Se)₃ based composition.
 42. The manufacturing meted for a thermoelectric semiconductor element according to claim 41, wherein the raw alloy comprises a composition in which 0.01 to 10% of excess Te is added to the stoichiometric composition of a compound thermoelectric semiconductor comprising 40 atomic % of Bi, 50 to 59 atomic % of Te, and 1 to 10 atomic % of Se.
 43. The manufacturing method for a thermoelectric semiconductor element according to claim 37, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 44. The manufacturing method for a thermoelectric semiconductor element according to claim 38, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temper no lower than 380° C. and no higher than 500° C.
 45. The manufacturing method for a thermoelectric semiconductor element according to claim 39, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 46. The manufacturing method for a thermoelectric semiconductor element according to claim 40, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 47. The manufacturing method for a thermoelectric semiconductor element according to claim 41, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 48. The manufacturing method for a thermoelectric semiconductor element according to claim 42, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 49. The manufacturing method for a thermoelectric semiconductor element according to claim 37, wherein, when the molten raw alloy is contacted with a surf of a cooling member so as to form plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 50. The manufacturing method for a thermoelectric semiconductor element according to claim 38, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 51. The manufacturing method for a thermoelectric semiconductor element according to claim 39, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shad raw thermoelectric semiconductor material is not quenched.
 52. The manufacturing method for a thermoelectric semiconductor element according to claim 40, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 53. The manufacturing method for a thermoelectric semiconductor element according to claim 41, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 54. The manufacturing method for a thermoelectric semiconductor element according to claim 42, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 55. The manufacturing method for a thermoelectric semiconductor element according to claim 43, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 56. The manufacturing method for a thermoelectric semiconductor element according to claim 44, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 57. The manufacturing method for a thermoelectric semiconductor element according to claim 45, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 58. The manufacturing method for a thermoelectric semiconductor element according to claim 46, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 59. The manufacturing method for a thermoelectric semiconductor element according to claim 47, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 60. The manufacturing method for a thermoelectric semiconductor element according to claim 48, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 61. The manufacturing method for a thermoelectric semiconductor element according to claim 37, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 62. The manufacturing method for a thermoelectric semiconductor element according to claim 38, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 63. The manufacturing method for a thermoelectric semiconductor element according to claim 39, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 64. The manufacturing method for a thermoelectric semiconductor element according to claim 40, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 65. The manufacturing method for a thermoelectric semiconductor element according to claim 41, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 66. The manufacturing method for a thermoelectric semiconductor element according to claim 42, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 67. The manufacturing method for a thermoelectric semiconductor element according to claim 43, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate sped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 68. The manufacturing method for a thermoelectric semiconductor element according to claim 44, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 69. The manufacturing method for a thermoelectric semiconductor element according to claim 45, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 70. The manufacturing method for a thermoelectric semiconductor element according to claim 46, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 um or greater.
 71. The manufacturing method for a thermoelectric semiconductor element according to claim 47, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 72. The manufacturing method for a thermoelectric semiconductor element according to claim 48, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 73. A manufacturing method for a thermoelectric module comprising: melting a raw alloy having a composition of P type thermoelectric semiconductor, and a raw alloy having a composition of N type thermoelectric semiconductor respectively; having the each raw alloy to be contacted with a surface of a cooling member to form plate shaped raw thermoelectric semiconductor materials having a composition of P type thermoelectric semiconductor and plate shaped raw thermoelectric semiconductor materials having a composition of N type thermoelectric semiconductor respectively; having the P type and N type raw thermoelectric semiconductor materials layered approximately parallel in a direction of plate thickness to form layered bodies; solidifying and forming the layered bodies to form compacts; applying pressure to each of the compacts having the compositions of P type and N type thermoelectric semiconductor in one of two axial directions which are crossing each other in a plane approximately perpendicular to the main layering direction of the raw thermoelectric semiconductor materials, while preventing deformation of the compact in the other axial direction; and thereby applying shear force in an axial direction approximately parallel to the main layering direction of the raw thermoelectric semiconductor materials; and plastically deforming the comes to form P type and N type thermoelectric semiconductor materials; cutting out P type and N type thermoelectric semiconductor elements from the P type and N type thermoelectric semiconductor materials so that a plane approximately perpendicular to the uniaxial direction in which the shear force is applied during the plastic deformation of the compact can be used as a contact surface with an electrode; arranging the P type and N type thermoelectric semiconductor elements so that the elements are aligned in the direction perpendicular to the axial direction of pressure application during plastic deformation of a compact, and also perpendicular to the direction of shear force by the pressure application; joining the P type and N type elements via a metal electrode to form a PN element pair.
 74. The manufacturing method for a thermoelectric module according to claim 73, wherein the raw alloy of each of the P type and N type thermoelectric semiconductors has a composition in which excess Te is added to a predetermined stoichiometric composition of a compound thermoelectric semiconductor.
 75. The manufacturing method for a thermoelectric module according to claim 74, wherein the stoichiometric composition of the P type compound thermoelectric semiconductor is a (Bi—Sb)₂Te₃ based composition.
 76. The manufacturing method for a thermoelectric module according to claim 75, wherein the raw alloy of the P type thermoelectric semiconductor comprises a composition in which 0.1 to 5% of excess Te is added to the stoichiometric composition of a compound thermoelectric semiconductor comprising 7 to 10 atomic % of Bi, 30 to 33 atomic % of Sb, and 60 atomic % of Te.
 77. The manufacturing method for a thermoelectric module according to claim 74, wherein the stoichiometric composition of the N type compound thermoelectric semiconductor is a Bi₂(Te—Se)₃ based composition.
 78. The manufacturing method for a thermoelectric module according to claim 77, wherein the raw alloy of the N type thermoelectric semiconductor wherein the raw alloy comprises a composition in which 0.01 to 10% of excess Te is added to the stoichiometric composition of a compound thermoelectric semiconductor comprising 40 atomic % of Bi, 50 to 59 atomic % of Te, and 1 to 10 atomic % of Se.
 79. The manufacturing method for a thermoelectric module according to claim 74, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 80. The manufacturing method for a thermoelectric module according to claim 75, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 81. The manufacturing method for a thermoelectric module according to claim 76, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 82. The manufacturing method for a thermoelectric module according to claim 77, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperate no lower than 380° C. and no higher than 500° C.
 83. The manufacturing method for a thermoelectric module according to claim 78, wherein solidification forming of the raw thermoelectric semiconductor materials is carried out by: along with applying pressure; heating the raw material at a temperature no lower than 380° C. and no higher than 500° C.
 84. The manufacturing method for a thermoelectric module according to claim 73, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shad raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 85. The manufacturing method for a thermoelectric module according to claim 74, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 86. The manufacturing method for a thermoelectric module according to claim 75, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 87. The manufacturing method for a thermoelectric module according to claim 76, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor material, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 88. The manufacturing method for a thermoelectric module according to claim 77, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 89. The manufacturing method for a thermoelectric module according to claim 78, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 90. The manufacturing method for a thermoelectric module according to claim 79, where, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 91. The manufacturing method for a thermoelectric module according to claim 80, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 92. The manufacturing method for a thermoelectric module according to claim 81, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 93. The manufacturing method for a thermoelectric module according to claim 82, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 94. The manufacturing method for a thermoelectric module according to claim 83, wherein, when the molten raw alloy is contacted with a surface of a cooling member so as to form the plate shaped raw thermoelectric semiconductor materials, the molten alloy is cooled and solidified at a rate at which 90% or more of a thickness of the formed plate shaped raw thermoelectric semiconductor material is not quenched.
 95. The manufacturing method for a thermoelectric module according to claim 73, wherein a rotational roll is used as the cooling member and is rotated at a rate at which the thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 96. The manufacturing method for a thermoelectric module according to claim 74, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 sun or greater.
 97. The manufacturing method for a thermoelectric module according to claim 75, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 98. The manufacturing method for a thermoelectric module according to claim 76, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 99. The manufacturing method for a thermoelectric module according to claim 77, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 100. The manufacturing method for a thermoelectric module according to claim 78, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 101. The manufacturing method for a thermoelectric module according to claim 79, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 102. The manufacturing method for a thermoelectric module according to claim 80, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the su of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 103. The manufacturing method for a thermoelectric module according to claim 81, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 104. The manufacturing method for a thermoelectric module according to claim 82, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 105. The manufacturing method for a thermoelectric module according to claim 83, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 106. The manufacturing method for a thermoelectric module according to claim 84, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 107. The manufacturing method for a thermoelectric module according to claim 85, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 108. The manufacturing method for a thermoelectric module according to claim 86, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 109. The manufacturing method for a thermoelectric module according to claim 87, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 110. The manufacturing method for a thermoelectric module according to claim 88, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 111. The manufacturing method or a thermoelectric module according to claim 89, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 112. The manufacturing method for a thermoelectric module according to claim 90, wherein a rotational roll is used as the cooling member and is red at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 113. The manufacturing method for a thermoelectric module according to claim 91, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 114. The manufacturing method for a thermoelectric module according to claim 92, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 115. The manufacturing method for a thermoelectric module according to claim 93, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater.
 116. The manufacturing method for a thermoelectric module according to claim 94, wherein a rotational roll is used as the cooling member and is rotated at a rate at which thickness of the plate shaped raw thermoelectric semiconductor material formed by supplying the molten raw alloy to the surface of the cooling member and cooling and solidifying the molten alloy is at least 30 μm or greater. 